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Base lubricants for green stamping:The effects of their structure and viscosity on tribological performance

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Friction 2023年第9期11卷 1741-1754页

作者： marko POLAJNar LucijaČOGA Mitjan KALIN Laboratory for Tribology and Interface Nanotechnology Faculty of Mechanical EngineeringUniversity of LjubljanaLjubljana 1000Slovenia

The requirements for green and sustainable manufacturing mean that stamping lubricants must be continuously re-evaluated and *** this investigation,the tribological performance of four base oils with different chemical structures(paraffinic and naphthenic)and viscosities(2 and 20 cSt),as well as water,was evaluated for the stamping of steel sheets and compared with a non-lubricated *** lubricants reduce the coefficient of friction and maintain a similar wear coefficient for steel sheets as in dry ***-viscosity(LV)naphthenic oil performs very like both high-viscosity(HV)oils.A surprising exception is the LV paraffinic oil,with several-times-higher friction and wear compared to dry *** is due to the excellent wetting-spreading and very low cohesion forces that enable oil to escape from extremely thin-film contacts because the viscosity is so low,leading to lubricant *** contrast,HV oils provide a sufficiently thick lubricating film,while strong cohesive forces help in the film’s strength,lessening wear,and reducing *** thin-film lubrication with LV oils,such as when stamping,it is thus extremely important that the lubricant’s wetting behaviour and viscosity are sufficient to provide enough film in the contact and prevent starvation,thus ensuring lower friction,less wear,and a longer lifetime of the contact.

关键词： stamping viscosity water paraffinic oil naphthenic oil wetting

artificial intelligence-based predictive model of nanoscale friction using experimental data

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Friction 2021年第6期9卷 1726-1748页

作者： marko PERČIĆ Saša ZELENIKA Igor MEZIĆ University of Rijeka Faculty of Engineering51000 RijekaCroatia University of Rijeka Centre for Micro-and Nanosciences and Technologies&Center for Artificial Intelligence and Cybersecurity51000 RijekaCroatia University of California Santa Barbara Department of Mechanical EngineeringSanta BarbaraCA 93105USA

A recent systematic experimental characterisation of technological thin films,based on elaborated design of experiments as well as probe calibration and correction procedures,allowed for the first time the determination of nanoscale friction under the concurrent influence of several process parameters,comprising normal forces,sliding velocities,and temperature,thus providing an indication of the intricate correlations induced by their interactions and mutual *** created the preconditions to undertake in this work an effort to model friction in the nanometric domain with the goal of overcoming the limitations of currently available models in ascertaining the effects of the physicochemical processes and phenomena involved in nanoscale *** to the stochastic nature of nanoscale friction and the relatively sparse available experimental data,meta-modelling tools fail,however,at predicting the factual *** on the acquired experimental data,data mining,incorporating various state-of-the-art machine learning(ML)numerical regression algorithms,is therefore *** results of the numerical analyses are assessed on an unseen test dataset via a comparative statistical *** is therefore shown that the black box ML methods provide effective predictions of the studied correlations with rather good accuracy levels,but the intrinsic nature of such algorithms prevents their usage in most practical *** programming-based artificial intelligence(AI)methods are consequently finally *** the marked complexity of the analysed phenomena and the inherent dispersion of the measurements,the developed AI-based symbolic regression models allow attaining an excellent predictive performance with the respective prediction accuracy,depending on the sample type,between 72%and 91%,allowing also to attain an extremely simple functional description of the multidimensional dependence of nanoscale friction on the studied variable process param

关键词： nanoscale friction thin films data mining machine learning(ML) predictive artificial intelligence(AI)-based model

On Abstract Third-Order Differential Equation and Its Applications

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Acta Mathematica Sinica,English Series 2023年第3期39卷 399-411页

作者： Belkacem CHAOUCHI Lakhdar BENAISSA marko KOSTIC Department of Mathematics Faculty of Science and TechnologyUniversity of Khemis MilianaKhemis MilianaAlgeria Department of Mathematics Faculty of ScienceUniversity of AlgiersAlgeria Faculty of Technical Sciences University of Novi SadTrg D.Obradovica 621125 Novi SadSerbia

In this paper,we consider an abstract third-order differential equation and deduce some results on the maximal regularity of its strict *** assume that the inhomogeneity appearing in the right-hand term of this equation belongs to some anistropic Holder *** illustrate our results by a BVP involving a 3D Laplacian posed in a cusp domain of R^(4).

关键词： Abstract third-order differential equation cusp domain strict solution

Design,Implementation and Performance of Synchronous Current Regulators for AC Drives

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Chinese Journal of Electrical Engineering 2018年第3期4卷 53-65页

作者： Fernando Briz marko Hinkkanen University of Oviedo GijonSpain Aalto University EspooFinland

Accurate,high bandwidth current control is a requirement for high performance vector controlled AC *** PI current regulators are the preferred solution for this *** and operation principles of synchronous PI current regulators are well ***,there are a number of issues that must be considered,especially when the drive must operate at high synchronous frequencies,including regulator design,effects due to discretization and the associated delays,voltage constraints and current sampling issues among *** degradation of the current regulator performance and consequently of the drive can occur otherwise.

关键词： Synchronous current regulators AC drives discretization discrete time models state feedback voltage saturation complex vector models

Amplitude Factorization Method in the Atmospheric Gravity-Wave Equation

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Communications in Computational Physics 2007年第5期2卷 993-1006页

作者： Rein Room marko Zirk Institute of Environmental Physics Tartu UniversityUlikooli 18Tartu 50090Estonia.

A novel amplitude factorization method is applied to solve a discrete buoyancy wave equation with arbitrary wind and temperature height *** solution is given in the form of a cumulative product of complex factors,which are computed by a nonlinear,inhomogeneous,two-member recurrence formula,initiated from a radiative condition on *** of the wave equation due to evanescent winds are eliminated by turbulent *** method provides an estimation of the minimal vertical resolution,required to attain a stable accurate *** areas of application of the developed numerical scheme are high resolution modelling of orographic waves for arbitrary orography in general atmospheric stratification conditions,and testing of adiabatic kernels of numerical weather prediction models.

关键词： Atmospheric gravity waves linear buoyancy wave equation arbitrary stratification numerical solution amplitude factorization method.

Modes of Exocytotic and Endocytotic Events in Tobacco BY-2 Protoplasts

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Molecular Plant 2011年第2期4卷 241-251页

作者： Vera Bandmann marko Kreft Ulrike Homann Institut fur Botanik Technische Universitat Darmstadt 64287 Darmstadt Germany Laboratory of Neuroendocrinology and Molecular Cell Physiology University of Ljubljana and Celica Biomedical Center Technology Park 24 1000 Ljubljana Slovenia

To analyze the kinetics and size of single exo- and endocytotic events in BY-2 protoplasts, we employed cellattached membrane capacitance measurements. These measurements revealed different modes of fusion and fission of single vesicles. In about half of the observed exocytotic events, fusion occurred transiently, which facilitates rapid recycling of vesicles. In addition, transient sequential or multi-vesicular exocytosis observed in some recordings can contribute to an increase in efficiency of secretory product release. Microscopic analysis of the timescale of cellulose and pectin deposition in protoplasts demonstrates that rebuilding of the cell wall starts soon after isolation of protoplasts and that transient fusion events can fully account for secretion of the required soluble material. The capacitance measurements also allowed us to investigate formation of the fusion pore. We speculate that regulation of secretion may involve control of the length and/or size of fusion pore opening. Together, the different kinetic modes of exo- and endocytosis revealed by capacitance measurements underline the complexity of this process in plants and provide a basis for future research into the underlying mechanisms. The fact that similar fusion/fission kinetics are present in plant and animal cells suggests that many of these mechanisms are highly conserved among eukaryotes.

关键词： Electrophysiology cell walls protein traffic and secretion BY-2 endocytosis exocytosis.

Particle penetration in fiber filters

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Particuology 2018年第5期16卷 70-79页

作者： Norbert Riefler Martina Ulrich marko Morshaiuser Udo Fritsching Process Engineering Institute of Materials ScienceBadgasteiner Strasse 328359BremenGermany Lydall Gutsche GmbH & Co.KG Hermann-Muth-Str.836039FuldaGermany Particles and Process Engineering University of BremenBibliothekstrasse 128359BremenGermany

Particle separation from gases is an important unit operation in manifold industrial applications,such as those conducted in environmental *** analysis of particle penetration and separation in fiber filters,standard dust particles (Al2O3)were loaded in the gas flow of a filter test facility and deposited within new and uncharged fiber *** loaded filters were analyzed by micro-computer tomography and scanning electron ***-dimensional tomograms of the samples show an exponential decay of the penetration depth of the *** dependency is confirmed by simulations conducted using the discrete element method coupled with computational fluid dynamics within unloaded and loaded fiber *** processes of particle separation at the fibers as well as the filtration efficiency and time-dependent filtering process are derived from the *** particle clustering in the filter medium and partial filter clogging are thus identified.

关键词： Particle filtration Fiber filter X-ray microtomography Computational fluid dynamics-discrete element method coupling High-fidelity simulation Transient mesh morphing

Population specific fitness response of Drosophila subobscura to lead pollution

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Insect Science 2013年第2期20卷 245-253页

作者： Bojan Kenig Marina Stamenkovic-Radak marko Andelkovic Institute for Biological Research Sinia Stankovic University of Belgrade Faculty of Biology University of Belgrade Serbian A cademy of Sciences and arts Belgrade Serbia

Differences in heavy metal tolerance among separate populations of the same species have often been interpreted as local adaptation. Persistence of differences after removing the stressor indicates that mechanisms responsible for the increased tolerance were genetically determined. Drosophila subobscura Collin （Diptera： Drosophilidae） pop- ulations were sampled from two localities with different history of heavy metal pollution, and reared for eight generations in the laboratory on a standard medium and on media with different concentrations of lead （Pb）. To determine whether flies from different natural populations exposed to the Pb-contaminated media in the laboratory show population spe- cific variability in fitness components over generations, experimental groups with different concentrations of lead were assayed in three generations （F2, Fs, and Fs） for fecundity, de- velopmental time, and egg-to-adult viability. On the contaminated medium, fecundity was reduced in later generations and viability was increased, irrespective of the environmental origin of populations. For both populations, developmental time showed a tendency of slowing down on media with lead. Faster development was observed in later generations. Preadaptation to contamination, meaning higher fecundity, higher viability, and faster egg to adult development in all studied generations, was found in D. subobscura originating from the locality with a higher level of heavy metal pollution,

关键词： environmental background fitness components heavy metal interpopulation differences laboratory evolution local adaptation

An experimental methodology for the concurrent characterization of multiple parameters influencing nanoscale friction

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Friction 2020年第3期8卷 577-593页

作者： marko PERCIC SaSa ZELENIKA Igor MEZIC Robert PETER Niksa KRSTULOVIC University of Rijeka Faculty of EngineeringVukovarska 58Rijeka 51000Croatia University of Rijeka Centre for Micro-and Nanosciences and TechnologiesRadmile Marej&ie 2Rjeka 51000 Croatia Department of Mechanical Engineering UC Santa BarbaraSanta BarbaraCA 93105USA University of Rijeka Department of PlysicsRadmile Matejtic 2Rijeka 51000Croatia Institute of Plnysics Bijenicka 46Zagreb 1000Croatia

A structured transdisciplinary method for the experimental determination of friction in the nanometric domain is proposed in this *** dependence of nanoscale friction on multiple process parameters on these scales,which comprise normal forces,sliding velocities,and temperature,was studied via the lateral force microscopy *** procedure used to characterize the stiffness of the probes used,and especially the influence of adhesion on the obtained results,is thoroughly *** analyzed thin films were obtained by using either atomic layer or pulsed laser *** developed methodology,based on elaborated design of experiments algorithms,was successfully implemented to concurrently characterize the dependence of nanoscale friction in the multidimensional space defined by the considered process *** enables the establishment of a novel methodology that extends the current state-of-the-art of nanotribological studies,as it allows not only the gathering of experimental data,but also the ability to do so systematically and concurrently for several influencing variables at ***,in turn,creates the basis for determining generalizing correlations of the value of nanoscale friction in any multidimensional experimental *** developments create the preconditions to eventually extend the available macro-and mesoscale friction models to a true multiscale model that will considerably improve the design,modelling and production of MEMS devices,as well as all precision positioning systems aimed at micro-and nanometric accuracy and precision.

关键词： nanoscale friction lateral force microscopy experimental determination methodology multivariate space contact mechanics