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Numerical prediction of the frictional losses in sliding bearings during start-stop operation

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Friction 2021年第3期9卷 583-597页

作者： florian KÖNiG Christopher sOUs Georg JACOBs institute for Machine Elements and systems Engineering Rheinisch-Westfälische Technische Hochschule Aachen UniversitySchinkelstraße 10Aachen 52062Germany

With the increased use of automotive engine start-stop systems,the numerical prediction and reduction of frictional losses in sliding bearings during starting and stopping procedures has become an important *** engineering practice,numerical simulations of sliding bearings in automotive engines are performed with statistical asperity contact models with empirical values for the necessary surface *** aim of this study is to elucidate the applicability of these approaches for the prediction of friction in sliding bearings subjected to start-stop *** this purpose,the friction performance of sliding bearings was investigated in experiments on a test rig and in transient mixed elasto-hydrodynamic simulations in a multi-body simulation environment(mixed-EHL/MBs).in mixed-EHL/MBs,the extended Reynold’s equation with flow factors according to Patir and Cheng has been combined on the one hand with the statistical asperity contact model according to Greenwood and Tripp and on the other hand with the deterministic asperity contact model according to *** detailed comparison of simulation and experimental results clarifies that the application of statistical asperity contact models with empirical values of the necessary inputs leads to large deviations between experiment and *** actual distribution and position of surface roughness,as used in deterministic contact modelling,is necessary for a reliable prediction of the frictional losses in sliding bearings during start-stop operation.

关键词： sliding bearing friction wearing-in contact model,mixed elasto-hydrodynamic simulation

Under false flag:using technical artifacts for cyber attack attribution

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Cybersecurity 2018年第1期1卷 729-748页

作者： florian skopik Timea Pahi Center for Digital safety and security AIT Austrian Institute of TechnologyAustriaGiefinggasse 4ViennaAustria

The attribution of cyber attacks is often *** consensus still is that little can be done to prosecute the perpetrators–and unfortunately,this might be right in many *** is however only of limited interest for the private industry is in the center of interest for nation *** if an attack was carried out in the name of a nation state is a crucial task for secret *** methods,tools and processes exist for network-and computer forensics that allow the collection of traces and *** are the basis to associate adversarial actions to threat ***,a serious problem which has not got the appropriate attention from research yet,are false flag campaigns,cyber attacks which apply covert tactics to deceive or misguide attribution attempts–either to hide traces or to blame *** this paper we provide an overview of prominent attack techniques along the cyber kill *** investigate traces left by attack techniques and which questions in course of the attribution process are answered by investigating these ***,we assess how easily traces can be spoofed and rate their relevancy with respect to identifying false flag campaigns.

关键词： Actor attribution Advanced persistent threats Technical indicators False flag campaigns

A Reduced Basis Approach for some Weakly stochastic Multiscale Problems

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Chinese Annals of Mathematics,series B 2012年第5期33卷 657-672页

作者： Claude LE BRis florian THOMiNEs CERMiCs Ecole Nationale des Ponts et Chaussees6 et 8 Avenue Blaise PascalCite DescartesChamps-sur-Marne77455 Marne-La-Vallée Cedex 2France iNRiA Rocquencourt MICMAC teamprojectDomaine de VoluceauBP10578153 Le Chesnay CedexFrance. iNRiA Rocquencourt MICMAC team-projectDomaine de VoluceauBP10578153 Le Chesnay CedexFrance Laboratoire Navier Ecole Nationale des Ponts et Chaussees6 et 8 Avenue Blaise PascalCite DescartesChamps-Sur-Marne77455 Marne-La-Vallée Cedex 2France.

in this paper,a multiscale problem arising in material science is *** problem involves a random coefficient which is assumed to be a perturbation of a deterministic coefficient,in a sense made precisely in the body of the *** homogenized limit is then computed by using a perturbation *** computation requires repeatedly solving a corrector-like equation for various configurations of the *** this purpose,the reduced basis approach is employed and adapted to the specific *** authors perform numerical tests that demonstrate the efficiency of the approach.

关键词： Reduced basis stochastic homogenization Perturbation approach

single-pulse ultrafast real-time simultaneous planar imaging of femtosecond laser-nanoparticle dynamics in flames

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Light(science & Applications) 2024年第10期13卷 2312-2320页

作者： Yogeshwar Nath Mishra Peng Wang florian J.Bauer Murthy s.Gudipati Lihong V.Wang Caltech Optical imaging Laboratory Andrew and Peggy Cheng Department of Medical EngineeringDepartment of Electrical EngineeringCalifornia Institute of Technology1200 East California BoulevardMail Code 138-78PasadenaCA 91125USA science Division Jet Propulsion LaboratoryCalifornia Institute of Technology4800 Oak Grove DrivePasadenaCA 91109USA Lehrstuhl für Technische Thermodynamik(LTT)and Erlangen Graduate school in Advanced Optical Technologies(sAOT) Universität Erlangen-NürnbergErlangen 91058Germany

The creation of carbonaceous nanoparticles and their dynamics in hydrocarbon flames are still debated in environmental,combustion,and material *** this study,we introduce single-pulse femtosecond laser sheetcompressed ultrafast photography(fsLs-CUP),an ultrafast imaging technique specifically designed to shed light on and capture ultrafast dynamics stemming from interactions between femtosecond lasers and nanoparticles in flames in a ***-CUP enables the first-time real-time billion frames-per-second(Gfps)simultaneous twodimensional(2D)imaging of laser-induced fluorescence(LiF)and laser-induced heating(LiH)that are originated from polycyclic aromatic hydrocarbons(PAHs)and soot particles,***,fsLs-CUP provides the real-time spatiotemporal map of femtosecond laser-soot interaction as elastic light scattering(ELs)at an astonishing 250 *** contrast to existing single-shot ultrafast imaging approaches,which are limited to millions of frames per second only and require multiple laser pulses,our method employs only a single pulse and captures the entire dynamics of laserinduced signals at hundreds of *** a single pulse does not change the optical properties of nanoparticles for a following pulse,thus allowing reliable spatiotemporal ***,we found that particle inception and growth are derived from *** essence,as an imaging modality,fsLs-CUP offers ultrafast 2D diagnostics,contributing to the fundamental understanding of nanoparticle’s inception and broader applications across different fields,such as material science and biomedical engineering.

关键词： pulse scattering dynamics

Quantum enhancement of accuracy and precision in optical interferometry

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Light(science & Applications) 2017年第1期6卷 90-94页

作者： florian Kaiser Panagiotis Vergyris Djeylan Aktas Charles Babin Laurent Labonté sébastien Tanzilli UniversitéCôte d’Azur Institut de Physique de Nice(INPHYNI)Nice 06108France Now at 3.Physikalisches institut Universität StuttgartStuttgart 70569Germany Now at Center for integrated Quantum science and Technology(iQsT) Stuttgart 70569Germany École Normale supérieure de Lyon Lyon 69364France

White-light interferometry is one of today’s most precise tools for determining the properties of optical *** achievable precision and accuracy are typically limited by systematic errors due to a high number of interdependent data-fitting ***,we introduce spectrally resolved quantum white-light interferometry as a novel tool for optical property measurements,notably,chromatic dispersion in optical *** exploiting both spectral and photon-number correlations of energy-time entangled photon pairs,the number of fitting parameters is significantly reduced,which eliminates systematic errors and leads to an absolute determination of the material *** comparing the quantum method to state-of-the-art approaches,we demonstrate the quantum advantage of 2.4 times better measurement precision,despite requiring 62 times fewer *** improved results are due to conceptual advantages enabled by quantum optics,which are likely to define new standards in experimental methods for characterising optical materials.

关键词： chromatic dispersion interferometry quantum optics quantum metrology

Zeckendorf representations with at most two terms to x-coordinates of Pell equations

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science China Mathematics 2020年第4期63卷 627-642页

作者： Carlos A.Gómez florian Luca Departamento de Matematicas Universidad del ValleCali 25360Colombia school of Mathematics University of the WitwatersrandWits 2050South Africa Max Planck institute for Mathematics Bonn 53111Germany Department of Mathematics Faculty of SciencesUniversity of OstravaOstrava 70103Czech Republic

in this paper,we find all positive squarefree integers d satisfying that the Pell equation X^2-d Y^2=±1 has at least two positive integer solutions(X,Y)and(X′,Y′)such that both X and X′have Zeckendorf representati... 详细信息

关键词： Pell equation Fibonacci numbers lower bounds for linear forms in logarithms reduction method

strategies to prevent and detect intraoperative spinal cord ischemia during complex aortic surgery:from drainages and biomarkers

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Neural Regeneration Research 2021年第4期16卷 678-679页

作者： Alexander Gombert florian simon Department of Vascular surgery University Hospital RWTH Aachen AachenGermany Department of Vascular and Endovascular surgery Heinrich-Heine-University of DüsseldorfDüsseldorfGermany

spinal cord ischemia(sCi),a frequent complication following open and endovascular thoracoabdominal aortic aneurysm(TAAA)repair,is a feared complication with relevant impact on a patient's quality of *** the early days of open TAAA repair,more than one third of the patients suffered from ***,due to improved preventive measures and the option of staged endovascular TAAA repair,10%of all patients are affected by spinal cord problems after TAAA repair(Rocha et al.,2020).

关键词： ischemia aortic sCi

An Optimised surface structure for Passive, Unidirectional Fluid Transport Bioinspired by True Bugs

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Journal of Bionic Engineering 2021年第2期18卷 375-386页

作者： sebastian Lifka florian Hischen Johannes Heitz Werner Baumgartner institute of Biomedical Mechatronics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria institute of Applied Physics Johannes Kepler University LinzAltenberger Straße 694040 LinzAustria

some true bug species use droplet-shaped,open-capillary structures for passive,unidirectional fluid transport on their body surface in order to spread a defensive fluid to protect themselves against *** this paper we investigated if the shape of the structures found on bugs(bug-structure)could be optimised with regard to better performance in unidirectional fluid ***,to use this kind of surface structure in technical applications where fluid surface interaction occurs,it is necessary to adapt the structure geometry to the contact angle between fluid and *** on the principal of operation of the droplet-shaped structures,we optimised the structure shape for better performance in targeted fluid flow and increase in flexibility in design of the structure *** adapt the structure geometry and the structure spacing to the contact angle,we implemented an equilibrium simulation of the,the structure surrounding,*** order to verify the functionality of the optimised structure,we designed and manufactured a *** testing this prototype with pure water used as fluid,the functionality of the optimised structure and the simulation could be *** kind of structure may be used on technical surfaces where targeted fluid transport is needed,*** of condensate in order to prevent the surface from mold growth,microfluidics,lab-on-a-chip applications and on microneedles for efficient drug/vaccine coating.

关键词： biomimetics true bugs liquid-surface interaction passive unidirectional fluid transport microfluidics lab-on-a-chip

Numerical Visualization of Grease Flow in a Gearbox

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Chinese Journal of Mechanical Engineering 2023年第2期36卷 220-233页

作者： Hua Liu florian Dangl Thomas Lohner Karsten stahl school of Engineering&Design Department of Mechanical EngineeringTechnical University of MunichGear Research Center(FZG)BoltzmannstraBe1585748 Garching near MunichGermany

Lubricating greases are widely used in *** gear drives and gearboxes with difficult sealing *** efficiency and heat balance of grease-lubricated gearboxes depend strongly on the lubrication mechanisms channeling and circulating,for which the grease flow is *** computational fluid dynamics opens up the possibility to visualize and understand the grease flow in gearboxes in more *** this study,a single-stage gearbox lubricated with an NLGi 1-2 grease was modeled by the finite-volume method to numerically investigate the fluid *** show that the rotating gears influence the grease sump only locally around the *** a low grease fill volume,the rotation of the gears is widely separated from the grease *** a high grease fill volume,a pronounced geargrease interaction results in a circulating grease flow around the *** simulated grease distributions show good accordance with high-speed camera recordings.

关键词： Lubrication Grease Transmission Gearbox Computational fluid dynamics