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Surroundings affect slip length dynamics in nanoscale friction through contact stiffness and damping

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Friction 2023年第2期11卷 216-227页

作者： Simona SKURATOVSKy Liron AGMON Enrico GNECCO Ronen berkovich Department of Chemical Engineering Ben-Gurion University of the NegevBeer-Sheva 8410501Israel Marian Smoluchowski Institute of Physics Jagiellonian UniversityLojasiewicza 11Krakow 30-348Poland Ilze Katz Institute for Nanoscience and Technology Ben-Gurion University of the NegevBeer-Sheva 8410501Israel

Friction force microscopy (FFM) explores the interaction in a sliding contact on the nanoscale, providing information on the frictional dynamics and lateral contact stiffness with lattice resolution. Recent FFM measurements on a NaCl crystal immersed in liquid (ethanol) surroundings displayed an increase of the effective contact stiffness, K_(eff), with the applied load, differently from similar measurements performed under ultra-high vacuum (UHV) conditions, where K_(eff) showed negligible load dependency. Additionally, under UHV conditions multiple slip length friction with increasing load was reported, while in ethanol surroundings only single (lattice unit length) slips were observed. Our current understanding of this behavior relates the transition from single jumps to multiple jumps dynamics to the normal load (manifested through the amplitude of the interaction potential at the contact, U0) and to the damping of the system. Here we have incorporated the effect of the load dependency on both U0 and K_(eff) within Prandtl‒Tomlinson based simulations, accompanied by variations in the damping coefficient of the system. Introducing the experimentally observed load dependency to K_(eff) resulted indeed in single slip jumps at critical damping, while multiple slip jumps were obtained at constant K_(eff). The average slip length increased with the normal load, particularly when the system became underdamped. Our work provides a glimpse on the relation between the characteristic observables in atomic-scale sliding friction (maximal slip forces, stiffness, and slip dynamics) with respect to their governing parameters (corrugation energy, effective stiffness, and damping). While common understanding in nanotribology relates the effect of surrounding media mainly to the interaction potential at the contact, here we show that the media can also greatly affect the elastic interaction, and consequently play an important role on the transition from single to multiple stick-s

关键词： friction force microscopy(FFM) nanoscale friction multiple jumps Prandtl‒Tomlinson model effective stiffness damping

Erosion,sediment transportation and accumulation in rivers

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International Journal of Sediment Research 2008年第2期23卷 93-105页

作者： N.I.ALEKSEEVSKIy K.M.berkovich R.S.CHALOV Head of the Hydrology Department Faculty of GeographyMoscow State UniversityMoscowRussiaProf Leading researcher Lab.of Soil Erosion and Fluvial ProcessesFaculty of GeographyMoscow State UniversityMoscowRussiaProf Head of the Lab.of Soil Erosion and Fluvial Processes Faculty of GeographyMoscow State UniversityMoscowRussiaProf

The present paper analyses the interrelation between erosion,sediment transportation and accumulation proposed by *** (1908-1983) and its further development in modern studies of river channel processes in ***-temporal linkages between erosion and accumulation are defined considering channel processes at different scales - river longitudinal profile,channel morphological patterns,alluvial bedforms (bars,dunes) and individual sediment *** between river geomorphic activity,flow transportation capacity and sediment budgets are established (sediment input and output; channel bed erosion and sediment entrainment into flow - termination of sediment transport and its deposition).Channel planforms,floodplain segments separated by the latter and alluvial channel bedforms are shown to be geomorphic expressions of sediment transport process at different spatial and temporal *** paper is dedicated to the 100th anniversary of ***,Professor of the Moscow State University,author of the book "River channel and erosion in its basin" (1955).That book is regarded in Russia as the pioneering work which initiated the complex hydrological and geographical studies of channel processes and laid a basis for the theory of unified fluvial erosion-accumulation process.

关键词： Channel processes Sediment Erosion and accumulation Longitudinal profile River channel patterns Channel bed morphology

Golay Code Clustering for Mobility Behavior Similarity Classification in Pocket Switched Networks

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通讯和计算机（中英文版） 2012年第4期9卷 466-472页

作者： Hongjun yU Tao Jing Dechang Chen Simon y. berkovich Department of Computer Science The George Washington University Washington DC 20052 USA School of Electronics and lnformation Engineering Beo＇ing JiaoTong University Beo＇ing P.R. China Department of Preventive Medicine and Biometrics Uniformed Services University of the Health Sciences Bethesda MD 20814USA

MICROBRIDGE TESTING OF yOUNG'S MODULUS AND RESIDUAL STRESS OF NICKEL FILM ELECTROPLATED ON SILICON WAFER

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 247-254页

作者： y.Zhou C.S.yang J.A. Chen G.F. Ding L. Wang M.J Wang y.M Zhang T.H Zhang Key Laboratory for Thin Film and Microfabrication of Ministry of Education Research Institute of Micro/Nanometer Science and Technology Shanghai Jiaotong University Shanghai 200030 China State Key Laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics The Chinese Academy of Sciences Beijing 100080 China.

Microbridge testing is used to measure the young's modulus and residual stresses of metallic *** film microbridges with widths of several hundred microns are fabricated by Microelectromechanical *** order to measure the mechanical properties of nickel film microbridges,special shaft structure is designed to solve the problem of getting the load--deflection curves of metal film microbridge by Nanoin--denter XP system with normal berkovich *** analysis of the micro--bridge load--deflection curve is proposed to evaluate the young's modulus and residual stress of the films *** calculated results based on the experimental measurements show that the average young's modulus and residual stress are around 190GPa and 175MPa respectively,while the young's modulus measured by Nano-hardness method on nickel film with silicon substrate is 186.8±7.34GPa.

关键词： nickel film microbridge MEMS mechanical property loadeflection measurement

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Some Technical Solutions for Environmental Protection System during Accidents at Nuclear Power Plants

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World Journal of Engineering and Technology 2017年第4期5卷 1-11页

作者： Sergey A. Kulyukhin Igor’ A. Rumer Viktor M. berkovich Gennadii S. Taranov Ivan V. yagodkin Viktor P. Osipov Sergey S. Skvortsov Leo N. Falkovskii Frumkin’ Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (IPCE RAS) Moscow Russia Institute “Atomenergoproekt” (AEP) Moscow Russia Institute of Physics and Power Engineering (IPPE) Obninsk Russia All-Russian Research Institute of Atomic Machine-Building (VNIIAM) Moscow Russia

The paper reports some technical solutions, which suggested or used for increasing of environmental protection during accidents at NPPs. For NNPs with two protective shells and pressure release system such as WWER-1000 a comprehensive, passive-mode environmental protection system of decontamination of the radioactive steam-air mixture from the containment and the intercontainment area was suggested. This system includes the “wet” stage (scrubbers, etc.), the “dry” stage (sorption module), and also an ejector, which in a passive mode is capable of solving the multi-purpose task of decontamination of the air-steam mixture. For WWER-440/230 NPPs three protection levels: 1) a jet-vortex condenser;2) the spray system;3) a sorption module were suggested and installed. For modern designs of new generation NPPs, which do not provide for pressure release systems, a new passive filtering system together with the passive heat-removal system, which can be used during severe accidents in case all power supply units become unavailable, was proposed and after modernization was installed at the KudanKulam NPP (India).

关键词： Nuclear Power Plants Severe Accident Environment Protection Radioactive Steam-Air Phase

A Nanoindentation Study on the Rheological Behaviour of Bituminous Binders

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武汉理工大学学报 2010年第17期32卷 47-50页

作者： LIU G VAN DE VEN M WU S P yU J y MOLENAAR A Faculty of Civil Engineering and Geosciences Delft University of TechnologyP.O. Box 50482600 GA Delftthe Netherlands Key Laboratory of Silicate Materials Science and Engineering of Ministry of Education Wuhan University of TechnologyWuhan 430070China

This paper reports the nanoindentation results of three bituminous binders,C-Fix,and standard penetration grade 40/60 bitumen and organo-montmorillonite (OMt) modified bitumen. Under a load applied by the berkovich diamond indenter,a loading and unloading history was recorded and the load-displacement curve was analyzed as a function of time. The software can directly give an output value of the modulus for C-Fix. However the result was dependent on the loading history. Due to increasing viscoelastic behaviour,the output value of the modulus for base bitumen was always negative,even with a very short unloading time. In conclusion,the modulus calculated by the software was not suitable for the bituminous binders due to their time-dependence. The nanoindentation curve during the loading phase of bitumen could be described by the adopted creep model. The results indicated that the OMt modified bitumen showed a high creep resistance than the base bitumen due to the OMt's reinforcement.

关键词： nanoindentation bitumen viscoelasticity creep

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Solid Particle Erosion of AISI 304 SS Caused by Alumina Particles

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Journal of Surface Engineered Materials and Advanced Technology 2024年第1期14卷 1-14页

作者： Juan Rodrigo Laguna-Camacho Celia María Calderón-Ramón Víctor Velázquez-Martínez Javier Calderón-Sánchez Gabriel Juárez-Morales Cristóbal Cortez-Domínguez Jorge Alberto Chagoya-Ramírez Jesús Enrique López-Calderón Paul Ramírez-Sánchez Silvia Marina Sánchez-yáñez Héctor Daniel López-Calderón Faculty of Electrical and Mechanical Engineering Universidad Veracruzana Poza Rica Veracruz Mexico Facultad de Ciencias Biolgicas y Agropecuarias Universidad Veracruzana Tuxpan Veracruz Mexico Facultad de Biologa Universidad Veracruzana Xalapa Veracruz Mexico

This research work was carried out with the aim of continuing to expand knowledge on the behaviour of AISI 304 stainless steel against solid particle erosion. In this particular case, the steel was subjected to the impact of alumina particles, which are hard abrasives with irregular and angular shapes. Different characterization techniques were applied to gain a better understanding of alumina. For instance, particle size distribution was obtained using the Analysette 28 Image Sizer and the particle size was between 300 - 400 µm. SEM and EDS analysis were used to know the morphology and chemical composition of both the abrasive particles and AISI 304 stainless steel. Additionally, mechanical properties values such as the hardness and young’s modulus of AISI 304 steel were attained using a berkovich indenter (model TTX-NHT, CSM Instruments). On the other hand, two tests were carried out for each impact angle used, 30˚, 45˚, 60˚ and 90˚, with a particle velocity of 24 ± 2 m/s and an abrasive flow rate of 63 ± 0.5 g/min, employing a test rig based on ASTM G76-95 standard. SEM images using two detectors, Backscattered Electron Detector (BED) and Low Electron Detector (LED), were employed to identify the wear mechanisms on the AISI 304 eroded surfaces at 30˚ and 90˚. Finally, the erosion rates of AISI 304 compared to those results reached by AISI 1018 steel and AISI 420 stainless steel tested under identical conditions in previous works.

关键词： Solid Particle Erosion AISI 304 Stainless Steel Alumina Particles Wear Mechanisms Erosion Rates