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Molecular dynamics simulation of the Stribeck curve: Boundary lubrication, mixed lubrication, and hydrodynamic lubrication on the atomistic level

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Friction 2023年第12期11卷 2342-2366页

作者： simon STEPHAN Sebastian SCHMITT Hans HASSE Herbert M.URBASSEK Laboratory of Engineering Thermodynamics(LTD) Department of Mechanical and Process EngieeringTU KaiserslauternRheinland-Pfalz 67663Germany Physics Department and Research Center(OPTIMAS) TU KaiserslauternRheinland-Pfalz 67663Germany

Lubricated contact processes are studied using classical molecular dynamics simulations for determining the entire range of the Stribeck ***,the lateral movement of two solid bodies at different gap height are *** each simulation,a rigid asperity is moved at constant height above a flat iron surface in a lubricating *** methane and decane are considered as *** three main lubrication regimes of the Stribeck curve and their transition regions are covered by the study:Boundary lubrication(significant elastic and plastic deformation of the substrate),mixed lubrication(adsorbed fluid layer dominates the process),and hydrodynamic lubrication(shear flow is set up between the surface and the asperity).We find the formation of a tribofilm in which lubricant molecules are immersed into the metal surface—not only in the case of scratching,but also for boundary lubrication and mixed *** formation of a tribofilm is found to have important consequences for the contact ***,the two fluids are found to show distinctly different behavior in the three lubrication regimes:For hydrodynamic lubrication(large gap height),decane yields a better tribological performance;for boundary lubrication(small gap height),decane shows a larger friction coefficient than methane,which is due to the different mechanisms observed for the formation of the tribofilm;the mixed lubrication regime can be considered as a transition regime between the two other ***,it is found that the nature of the tribofilm depends on the lubricant:While methane particles substitute substrate atoms sustaining mostly the crystalline structure,the decane molecules distort the substrate surface and an amorphous tribofilm is formed.

关键词： boundary lubrication mixed lubrication hydrodynamic lubrication molecular dynamics simulation tribofilm

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Experimental and Numerical Analysis of a PCM-Integrated Roof for Higher Thermal Performance of Buildings

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Journal of Thermal Science 2024年第2期33卷 522-536页

作者： simon François RUIZ-VALERO Letzai GIRARD Aymeric GALLEGUILLOS Hector Centro de Desarrollo Urbano Sustentable(CEDEUS) Pontificia Universidad Católica de Chile7500000SantiagoChile Facultad de Ciencias e Ingeniería Pontificia Universidad Católica Madre y Maestra(PUCMM)10103Santo DomingoDominican Republic LMGC IMT Mines AlesUniv MontpellierCNRS30100AlèsFrance Facultad de Ingeniería y Ciencias Universidad Adolfo Ibañez2520000Viña del MarChile Centro de Desarrollo Energético Antofagasta(CDEA) Universidad de Antofagasta1240000AntofagastaChile

Phase change materials(PCMs) designate materials able to store latent *** change state from solid to liquid over a defined temperature *** process is reversible and can be used for thermo-technical *** present paper aims to study the thermal performance of an inorganic eutectic PCM integrated into the rooftop slab of a test room and analyze its potential for building thermal *** experiment is conducted in two test rooms in Antofagasta(Chile) during summer,fall,and *** PCM is integrated into the rooftop of the first test room,while the roof panel of the second room is a sealed air *** work introduces a numerical model,which is built using the finite difference method and used to simulate the rooms' thermal *** thermal simulations of the PCM room are performed for other Chilean locations to evaluate and compare the capability of the PCM panel to store latent heat thermal energy in different *** show that the indoor temperature of the PCM room in Antofagasta varies only 21.1℃±10.6℃,while the one of the air-panel room varies 28.3℃±18.5℃.Under the experiment's conditions,the PCM room's indoor temperature observes smoother diurnal fluctuations,with lower maximum and higher minimum indoor temperatures than that of the air-panel *** simulations in other cities show that the PCM panel has a better thermal performance during winter,as it helps to maintain or increase the room temperature by some degrees to reach comfort *** demonstrates that the implementation of such PCM in the building envelope can effectively reduce space heating and cooling needs,and improve indoor thermal comfort in different climates of Chile.

关键词： phase change material thermal energy storage building space heating and cooling energy efficiency designbuilder

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A novel role for mitochondrial fission in macrophages: trained innate immunity induced by beta-glucan

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Cellular & Molecular Immunology 2023年第8期20卷 864-866页

作者： Anna Brichkina Hans-Uwe simon Institute of Systems Immunology Center for Tumor Biology and ImmunologyPhilipps University of Marburg35043MarburgGermany Member of the German Center for Lung Research(DZL) Philipps University of Marburg35043MarburgGermany Laboratory of Molecular Immunology Institute of Fundamental Medicine and BiologyKazan Federal University420012KazanRussia Institute of Pharmacology University of Bern3010BernSwitzerland Institute of Biochemistry Brandenburg Medical School16816NeuruppinGermany

In a recent paper published in Nature Immunology,Ding et *** new insights into the mechanism of how trained innate immunity could eradicate *** authors demonstrated that yeast-derived whole beta-glucan particles(WGP)increased the responsiveness of lung interstitial macrophages to tumor-derived factors associated with the subsequent inhibition of tumor metastasis through enhanced cytotoxicity to cancer *** authors identified the metabolic sphingolipid–mitochondrial fission axis in WGP-trained macrophages as the key pathway responsible for this phenomenon and categorized it as a mechanism of trained innate immunity[1].

关键词： subsequent insight immunity

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Evaluating organic acids as alternative leaching reagents for rare earth elements recovery from NdFeB magnets

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Journal of Rare Earths 2023年第4期41卷 621-631页

作者： Sahar Belfqueh Alain Seron simon Chapron Guilhem Arrachart Nourredine Menad BRGM Direction de l'Eaude l'Environnementdes Procédés et AnalysesOrleansFrance ICSM Univ.MontpellierCEACNRSENSCMMarcouleFrance

This study proposes an advanced leaching method using organic acids to recover rare earth elements(REEs)from NdFeB permanent magnets from end-of-life computers hard disk drives(HDDs).The end-oflife HDDs were first dismantled in order to recover NdFeB magnets,which were then thermally demagnetized at 350℃during 30 min before crushing in a ball mill under inert *** electron microscopy/energy dispersive X-ray spectroscopy(SEM/EDS)analyses performed on the NdFeB magnets show the heterogeneous structure containing the major matric phase Nd_(2)Fe_(14)B and the REEsrich phase containing Nd and Pr ***,X-ray diffraction(XRD)and Mossbauer spectroscopy(MS)analyses on the ground NdFeB magnet show that grinding NdFeB magnets under inert atmosphere helps to minimize its *** analysis shows that the composition of the ground sample is Nd:22.8 wt%,Pr:3.3 wt%,Dy:1.2 wt%,Fe:62.6 wt%,Co:1.5 wt%,B:0.9 wt%,Ni:0.6 wt%.Diagrams of speciation and equilibrium phases(E_(h) ***)were calculated to determine the predominance of the formed species in the REEs-organic acids *** influence of the organic acid type(acetic acid,formic acid,citric acid and tartaric acid),the acid concentration(10 vol%,up to saturation),and the solid/liquid(S/L)ratio(0.5%-10%)on NdFeB magnets leaching was investigated employing an optimal experimental design conceived by the statistical software *** acid(CH_(3)COOH)shows the highest leaching performance of REEs,allowing leaching yields over 90%for Nd,Dy and Pr in the acid concentration range of 1.6-10 mol/L and the S/L ratio range of 0.5%-5%at a temperature of 60℃.The results presented in this investigation suggest that REEs can be recovered from magnets of end-of-life HDDs using an eco-friendly method assisted by organic acids.

关键词： NdFeB magnets Rare earth elements Leaching Organic acids Acetic acid

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Suppression of Self-Discharge in Aqueous Supercapacitor Devices Incorporating Highly Polar Nanofiber Separators

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Energy & Environmental Materials 2023年第3期6卷 74-86页

作者： Wesley G.Buxton simon G.King Vlad Stolojan Advanced Technology Institute University of SurreyGuildford SurreyGU27XHUK

One of the major problems limiting the applications of electric double-layer(EDLC)supercapacitor devices is their inability to maintain their cell voltage over a significant ***-discharge is a spontaneous decay in charged energy,often resulting in fully depleted devices in a matter of ***,a new method for suppressing this self-discharge phenomenon is proposed by using directionally polarized piezoelectric electrospun nanofiber films as separator *** engineering of polyvinylidene fluoride(PVDF)nanofiber films containing a small concentration of sodium dodecyl sulfate(SDS)results in a high proportion of polarβphases,reaching 380.5%of the total *** polarity into the separator material provides a reverse-diode mechanism in the device,such that it drops from an initial voltage of 1.6 down to 1 V after 10 h,as opposed to 0.3 V with a nonpolarized,commercial separator ***,the energy retained for the polarized separator is 37%and 4%for the nonpolarized separator,making supercapacitors a more attractive solution for long-term energy storage.

关键词： piezoelectric polar nanofibers PVDF separators self-discharge supercapacitors

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3D-QSAR analysis of a new type of acetylcholinesterase inhibitors

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Science China(Life Sciences) 2007年第6期50卷 726-730页

作者： LEE simon M. Y Institute of Chinese Medical Sciences University of Macao Av. Padre Tomas Pereira S. J. Taipa Macao China

Acetylcholinesterase (AChE) inhibitors are an important class of medicinal agents used for the treatment of Alzheimer’s disease. A screening model of AChE inhibitor was used to evaluate the inhibition of a series of phenyl pentenone derivatives. The assay result showed that some compounds displayed higher inhibitory effects. In order to study the relationship between the bioactivities; the structures, 26 compounds with phenyl pentenone scaffold were analyzed. A 3D-QSAR model was constructed using the method of comparative molecular field analysis (CoMFA). The results of cross-validated R[2]cv=0.629, non-cross-validated R[2]=0.972, SE=0.331,; F=72.41 indicate that the 3D-model possesses an ability to predict the activities of new inhibitors,; the CoMFA model would be useful for the future design of new AChE inhibitors.

关键词： acetylcholinesterase (AChE), comparative molecular field analysis (CoMFA), phenyl pentenone derivatives

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Pancreatitis: Preventing catastrophic haemorrhage

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World Journal of Gastroenterology 2017年第30期23卷 5460-5468页

作者： Richard PT Evans Moustafa Mabrouk Mourad Gunraj Pall simon G Fisher simon R Bramhall Russel’s Hall Hospital Department of Surgery the Wye Valley NHS Trust

Pancreatitis represents nearly 3% of acute admissions to general surgery in United Kingdom hospitals and has a mortality of around 1%-7% which increases to around 10%-18% in patients with severe pancreatitis. Patients at greatest risk were those identified to have infected pancreatic necrosis and/or organ failure. This review seeks to highlight the potential vascular complications associated with pancreatitis that despite being relatively uncommon are associated with mortality in the region of 34%-52%. We examine the current evidence base to determine the most appropriate method by which to image and treat pseudo-aneurysms that arise as the result of acute and chronic inflammation of pancreas. We identify how early recognition of the presence of a pseudo-aneurysm can facilitate expedited care in an expert centre of a complex pathology that may require angiographic, percutaneous, endoscopic or surgical intervention to prevent catastrophic haemorrhage.

关键词： Complication of pancreatitis Splenicartery Pancreatitis Haemorrhage Pseudoaneurysm

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Object removal from complex videos using a few annotations

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Computational Visual Media 2019年第3期5卷 267-291页

作者： Thuc Trinh Le Andrés Almansa Yann Gousseau simon Masnou LTCI T′el′ecom ParisTechUniversit′e Paris-Saclay75013 ParisFrance MAP5 CNRS&Universit′e Paris Descartes75006 ParisFrance Univ Lyon Universit′e Claude Bernard Lyon 1CNRS UMR 5208Institut Camille Jordan69622 VilleurbanneFrance

We present a system for the removal of objects from videos. As input, the system only needs a user to draw a few strokes on the first frame, roughly delimiting the objects to be removed. To the best of our knowledge, this is the first system allowing the semi-automatic removal of objects from videos with complex backgrounds. The key steps of our system are the following: after initialization, segmentation masks are first refined and then automatically propagated through the video. Missing regions are then synthesized using video inpainting techniques. Our system can deal with multiple, possibly crossing objects, with complex motions, and with dynamic textures. This results in a computational tool that can alleviate tedious manual operations for editing high-quality videos.

关键词： object removal object segmentation object tracking video inpainting video completion

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An explainable AI framework for robust and transparent data-driven wind turbine power curve models

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Energy and AI 2024年第1期15卷 312-327页

作者： simon Letzgus Klaus-Robert Müller Machine Learning Group Technische Universitβe BerlinStraβe des 17.Juni 135Berlin10623Germany Berlin Institute for the Foundations of Learning and Data Berlin10587Germany Department of Artificial Intelligence Korea UniversitySeoul136-713South Korea Max Planck Institute for Informatics Saarbrücken66123Germany

In recent years,increasingly complex machine learning methods have become state-of-the-art in modelling wind turbine power curves based on operational *** these methods often exhibit superior performance on test sets,they face criticism due to a perceived lack of transparency and concerns about their robustness in dynamic,non-stationary environments encountered by wind *** this work,we address these issues and present a framework that leverages explainable artificial intelligence methods to gain systematic insights into data-driven power curve *** its core,we propose a metric to quantify how well a learned model strategy aligns with the underlying physical principles of the *** novel tool enables model validation beyond the conventional error metrics in an automated *** demonstrate,for instance,its capacity as an indicator for model generalization even when limited data is ***,it facilitates understanding how decisions made during the machine learning development process,such as data selection,pre-processing,or training parameters,affect learned *** a result,we obtain physically more reasonable models,a prerequisite not only for robustness but also for meaningful insights into turbine operation by domain *** latter,we illustrate in the context of wind turbine performance *** summary,the framework aims to guide researchers and practitioners alike toward a more informed selection and utilization of data-driven wind turbine power curve models.

关键词： Explainable AI(XAI) Machine learning Wind energy Wind turbine power curve SCADA Condition monitoring

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Tsunami Balls:A Granular Approach to Tsunami Runup and Inundation

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Communications in Computational Physics 2008年第1期3卷 222-249页

作者： Steven N.Ward simon Day Institute of Geophysics and Planetary Physics University of CaliforniaSanta CruzCA 95064USA.

This article develops a new,granular approach to tsunami runup and *** small grains employed here are not fluid,but bits,or balls,of tsunami *** careful formulation of the ball accelerations,both wave-like and flood-like behaviors are accommodated so tsunami waves can be run seamlessly from deep water,through wave breaking,to the final surge onto shore and back *** deep water,tsunami balls track according long wave ray *** land,tsunami balls behave like a water *** shallow water,the balls embody both deep water and on land *** modeling several 2-D and 3-D cases,we find that wave breaking generally causes relative runup to increase with beach slope and wave period and decrease with input wave *** of their highly non-linear nature,runup and inundation are best considered to be random processes rather than deterministic *** and observations hint that for uniform input waves,normalized runup statistics everywhere follow a single skewed distribution with a spread between 1/2 and 2 times its mean.

关键词： Water wave tsunami run up.

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