Academic literature on the topic 'Contact interface evolution'
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Journal articles on the topic "Contact interface evolution"
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Marshall, M. B., R. Lewis, R. S. Dwyer-Joyce, U. Olofsson, and S. Björklund. "Experimental Characterization of Wheel-Rail Contact Patch Evolution." Journal of Tribology 128, no. 3 (March 21, 2006): 493–504. http://dx.doi.org/10.1115/1.2197523.
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The contact area and pressure distribution in a wheel/rail contact is essential information required in any fatigue or wear calculations to determine design life, re-grinding, and maintenance schedules. As wheel or rail wear or surface damage takes place the contact patch size and shape will change. This leads to a redistribution of the contact stresses. The aim of this work was to use ultrasound to nondestructively quantify the stress distribution in new, worn, and damaged wheel-rail contacts. The response of a wheel/rail interface to an ultrasonic wave can be modeled as a spring. If the contact pressure is high the interface is very stiff, with few air gaps, and allows the transmission of an ultrasonic sound wave. If the pressure is low, interfacial stiffness is lower and almost all the ultrasound is reflected. A quasistatic spring model was used to determine maps of contact stiffness from wheel/rail ultrasonic reflection data. Pressure was then determined using a parallel calibration experiment. Three different contacts were investigated; those resulting from unused, worn, and sand damaged wheel and rail specimens. Measured contact pressure distributions are compared to those determined using elastic analytical and numerical elastic-plastic solutions. Unused as-machined contact surfaces had similar contact areas to predicted elastic Hertzian solutions. However, within the contact patch, the numerical models better reproduced the stress distribution, as they incorporated real surface roughness effects. The worn surfaces were smoother and more conformal, resulting in a larger contact patch and lower contact stress. Sand damaged surfaces were extremely rough and resulted in highly fragmented contact regions and high local contact stress.
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Peng, Wei, James Kiely, and Yiao-Tee Hsia. "Wear Analysis of Head-Disk Interface During Contact." Journal of Tribology 127, no. 1 (January 1, 2005): 171–79. http://dx.doi.org/10.1115/1.1843832.
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To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultralow fly height, the intermittent–continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a nonlinear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a three-dimensional (3D) sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.
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Tiezzi, Paolo, and Imin Kao. "Modeling of Viscoelastic Contacts and Evolution of Limit Surface for Robotic Contact Interface." IEEE Transactions on Robotics 23, no. 2 (April 2007): 206–17. http://dx.doi.org/10.1109/tro.2006.889494.
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Sahli, R., G. Pallares, C. Ducottet, I. E. Ben Ali, S. Al Akhrass, M. Guibert, and J. Scheibert. "Evolution of real contact area under shear and the value of static friction of soft materials." Proceedings of the National Academy of Sciences 115, no. 3 (January 2, 2018): 471–76. http://dx.doi.org/10.1073/pnas.1706434115.
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The frictional properties of a rough contact interface are controlled by its area of real contact, the dynamical variations of which underlie our modern understanding of the ubiquitous rate-and-state friction law. In particular, the real contact area is proportional to the normal load, slowly increases at rest through aging, and drops at slip inception. Here, through direct measurements on various contacts involving elastomers or human fingertips, we show that the real contact area also decreases under shear, with reductions as large as 30%, starting well before macroscopic sliding. All data are captured by a single reduction law enabling excellent predictions of the static friction force. In elastomers, the area-reduction rate of individual contacts obeys a scaling law valid from micrometer-sized junctions in rough contacts to millimeter-sized smooth sphere/plane contacts. For the class of soft materials used here, our results should motivate first-order improvements of current contact mechanics models and prompt reinterpretation of the rate-and-state parameters.
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Pei, Yu, Babak Rezaei, Xuyang Zhang, Zichuang Li, Hangjia Shen, Minghui Yang, and Jiacheng Wang. "Interface catalysis by Pt nanocluster@Ni3N for bifunctional hydrogen evolution and oxygen evolution." Materials Chemistry Frontiers 4, no. 9 (2020): 2665–72. http://dx.doi.org/10.1039/d0qm00326c.
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Pt@Ni3N catalysts with plentiful contact between Ni3N and Pt species were fabricated by a facile strategy. The Pt@Ni3N with low amount of Pt clusters shows excellent electrocatalytic activity of HER and OER in alkaline media.
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Chopra, Kriti, Bhawna Burdak, Kaushal Sharma, Ajit Kembhavi, Shekhar C. Mande, and Radha Chauhan. "CoRNeA: A Pipeline to Decrypt the Inter-Protein Interfaces from Amino Acid Sequence Information." Biomolecules 10, no. 6 (June 22, 2020): 938. http://dx.doi.org/10.3390/biom10060938.
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Decrypting the interface residues of the protein complexes provides insight into the functions of the proteins and, hence, the overall cellular machinery. Computational methods have been devised in the past to predict the interface residues using amino acid sequence information, but all these methods have been majorly applied to predict for prokaryotic protein complexes. Since the composition and rate of evolution of the primary sequence is different between prokaryotes and eukaryotes, it is important to develop a method specifically for eukaryotic complexes. Here, we report a new hybrid pipeline for predicting the protein-protein interaction interfaces in a pairwise manner from the amino acid sequence information of the interacting proteins. It is based on the framework of Co-evolution, machine learning (Random Forest), and Network Analysis named CoRNeA trained specifically on eukaryotic protein complexes. We use Co-evolution, physicochemical properties, and contact potential as major group of features to train the Random Forest classifier. We also incorporate the intra-contact information of the individual proteins to eliminate false positives from the predictions keeping in mind that the amino acid sequence of a protein also holds information for its own folding and not only the interface propensities. Our prediction on example datasets shows that CoRNeA not only enhances the prediction of true interface residues but also reduces false positive rates significantly.
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Li, Dongwu, Chao Xu, Ruozhang Li, and Wenming Zhang. "Contact parameters evolution of bolted joint interface under transversal random vibrations." Wear 500-501 (July 2022): 204351. http://dx.doi.org/10.1016/j.wear.2022.204351.
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PEYRET, N., J. L. DION, G. CHEVALLIER, and P. ARGOUL. "MICRO-SLIP INDUCED DAMPING IN PLANAR CONTACT UNDER CONSTANT AND UNIFORM NORMAL STRESS." International Journal of Applied Mechanics 02, no. 02 (June 2010): 281–304. http://dx.doi.org/10.1142/s1758825110000597.
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The friction between interfaces at bolted joints plays a major role in the damping of structures. This paper deals with the energy losses caused by micro-slips in the joints. The aim of this study is to define in an analytical way these energy dissipation mechanisms which we examine through the analysis of a new benchmark: the flexural vibration of a clamped-clamped beam with original positioning of the interfaces. The joints exhibit the behavior of an interface under constant and uniform normal stress. The stress and strain values are computed at the joints under the assumption of quasi-static motion. This model allows us to understand the evolution of the slip and stick regions along the joint interfaces during the loading process. The expressions of the strain and stress fields during each phase of the loading process are derived. These lead to the quantification of the dissipated energy within the interface. Using this formula, a nonlinear loss factor can then be computed. In the final part of the paper, the dynamic response of the beam is calculated using this nonlinear loss factor.
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Si, Ting, Tong Long, Zhigang Zhai, and Xisheng Luo. "Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder." Journal of Fluid Mechanics 784 (November 4, 2015): 225–51. http://dx.doi.org/10.1017/jfm.2015.581.
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The interaction of cylindrical converging shock waves with a polygonal heavy gas cylinder is studied experimentally in a vertical annular diaphragmless shock tube. The reliability of the shock tube facility is verified in advance by capturing the cylindrical shock movements during the convergence and reflection processes using high-speed schlieren photography. Three types of air/SF6 polygonal interfaces with cross-sections of an octagon, a square and an equilateral triangle are formed by the soap film technique. A high-speed laser sheet imaging method is employed to monitor the evolution of the three polygonal interfaces subjected to the converging shock waves. In the experiments, the Mach number of the incident cylindrical shock at its first contact with each interface is maintained to be 1.35 for all three cases. The results show that the evolution of the polygonal interfaces is heavily dependent on the initial conditions, such as the interface shapes and the shock features. A theoretical model for circulation initially deposited along the air/SF6 polygonal interface is developed based on the theory of Samtaney & Zabusky (J. Fluid Mech., vol. 269, 1994, pp. 45–78). The circulation depositions along the initial interface result in the differences in flow features among the three polygonal interfaces, including the interface velocities and the perturbation growth rates. In comparison with planar shock cases, there are distinct phenomena caused by the convergence effects, including the variation of shock strength during imploding and exploding (geometric convergence), consecutive reshocks on the interface (compressibility), and special behaviours of the movement of the interface structures (phase inversion).
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Ding, H., B. Q. Chen, H. R. Liu, C. Y. Zhang, P. Gao, and X. Y. Lu. "On the contact-line pinning in cavity formation during solid–liquid impact." Journal of Fluid Mechanics 783 (October 26, 2015): 504–25. http://dx.doi.org/10.1017/jfm.2015.574.
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We investigate the cavity formation during the impact of spheres and cylinders into a liquid pool by using a combination of experiments, simulations and theoretical analysis, with particular interest in contact-line pinning and its relation with the subsequent cavity evolution. The flows are simulated by a Navier–Stokes diffuse-interface solver that allows for moving contact lines. On the basis of agreement on experimentally measured quantities such as the position of the pinned contact line and the interface shape, we investigate flow details that are not accessible experimentally, identify the interface regions in the cavity formation and examine the geometric effects of impact objects. We connect wettability, inertia, geometry of the impact object, interface bending and contact-line position with the contact-line pinning by analysing the force balance at a pinned meniscus, and the result compares favourably with those from simulations and experiments. In addition to adjusting the interface bending, the object geometry also has a significant effect on the magnitude of low pressure in the liquid and the occurrence of flow separation. As a result, it is easier for an object with sharp edges to generate a cavity than a smooth object. A theoretical model based on the Rayleigh–Besant equation is developed to provide a quantitative description of the radial expansion of the cavity after the pinning of the contact line. The accuracy of the solution is greatly affected by the geometrical information on the interface connected to the pinned meniscus, showing the dependence of the global cavity dynamics on the local flows around the pinned contact line. Vertical ripple propagation on the cavity wall is found to follow the dispersion relation for the perturbation evolution on a hollow jet.
Dissertations / Theses on the topic "Contact interface evolution"
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Lee, Ji Hyung. "In-situ Analysis of the Evolution of Surfaces and Interfaces under Applied Coupled Stresses." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707308/.
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To study the effect of the substrate support on the nanoscale contact, three different regimes, i.e., graphene on rigid (ultra-crystalline diamond) and on elastic (Polydimethylsiloxane) supports and free-standing graphene, were considered. The contribution of the graphene support to the mechanical and electrical characteristics of the graphene/metal contact was studied using the conductive atomic force microscopy (AFM) technique.The results revealed that the electrical conductivity of the graphene/metal contact highly depends on the nature of the graphene support. The conductivity increased when transitioning from suspended to elastic and then to rigid substrates, which is attributed to the changes in the contact area being higher for the suspended graphene and lower for the rigid substrate. The experimental observations showed good agreement with theoretical results obtained from modeling of the studied material systems. Further, the results indicated that in addition to the substrate support, the nature of the contact, static or dynamic, results in large variations of the electrical conductivity of the graphene/metal contacts. In case of the static mode, the contact made with supported graphene was very stable for a wide range of applied normal loads. Transitioning to the dynamic mode led to instability of the graphene/metal contact as demonstrated by lowering in the electrical conductivity values. This transition was even more pronounced for free-standing graphene which is attributed to graphene sagging during rapid scanning of the tip over the graphene surface. This study creates a new knowledge on understanding of the nanoscale contacts forming with 2D materials thus enabling further advances in the applications of 2D materials in highly stable and reliable electronic devices.
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Rauchecker, Maximilian [Verfasser], Harald [Akademischer Betreuer] Garcke, Mathias [Akademischer Betreuer] Wilke, and Gieri [Akademischer Betreuer] Simonett. "Evolution of interfaces in two-phase problems with ninety degree contact angle / Maximilian Rauchecker ; Harald Garcke, Mathias Wilke, Gieri Simonett." Regensburg : Universitätsbibliothek Regensburg, 2019. http://d-nb.info/1201160642/34.
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Creazzo, Fabrizio. "Oxygen evolution reaction at cobalt oxides/water interfaces : heterogeneous electrocatalysis by DFT-MD simulations & metadynamics Ab initio molecular dynamics study of an aqueous NaCl solution under an electric field Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts Ionic Diffusion and Proton Transfer in Aqueous Solutions under an Electric Field: State-of-The-Art Ionic diffusion and proton transfer of MgCl2 and CaCl2 aqueous solutions: an ab initio study under electric field DFT-MD of the (110)-Co 3 O 4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment Enhanced conductivity of water at the electrified air–water interface: a DFT-MD characterization Ions tune interfacial water structure and modulate hydrophobic interactions at silica surfaces." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE012.
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Dans cette thèse, des simulations DFT-MD couplées à des techniques inno-vantes de métadynamique, sont appliquées pour acquérir une compréhensionglobale des interfaces aqueuses d'oxyde de cobalt Co3O4 et CoO(OH) dansla catalyse de la réaction d'évolution de l'oxygène (OER), et ainsi éventuellement aider à la conception de nouveaux catalyseurs basés sur des matériaux non précieux, un domaine clé de la recherche scientifique et technologique, particulièrement important pour l'économie de l'hydrogène, pour les technologies vertes dans une période de temps avec une demande toujours plus croissanteen énergie verte. Dans cette thèse, nous révélons étape par étape les mécanismes de l'OER sur les électrocatalyseurs aqueux d'oxyde de cobalt Co3O4 etCoO(OH) via de nouvelles techniques de métadynamique.Jusqu'à présent, la littérature n'a jamais pris en compte les modificationsau niveau atomique de la structure des électrodes ainsi que de l'eau interfaciale dans leur modélisation des processus OER. Ce manque de connaissances représente clairement un obstacle important au développement de catalyseurs améliorés, qui pourrait être surmonté en utilisant des méthodes capables de suivre les caractéristiques catalytiques de l'OER à l'échelle atomique. Pour la première fois, nous montrons combien il est important de prendre en considération la présence de l'environnement aqueux dans la caractérisation structurale des surfaces du catalyseur, c'est-à-dire (110)-Co3O4 et (0001)-CoO(OH) dans ce travail. Une caractérisation détaillée des propriétés chimiques et physiques des interfaces aqueuses est fournie (la structure, la dynamique, la spectroscopie, le champ électrique), pour les surfaces (110)-Co3O4 et (0001)-CoO(OH) en contact avec l'eau liquide.Une étude détaillée de l'OER est présentée non seulement du point de vue descatalyseurs, mais aussi en abordant le rôle de l'environnement de l'eau dans leprocessus catalytique, ce qui n'a pas été fait auparavant dans la littérature. En conséquence, l'OER en phase gazeuse et en phase liquide sont étudiés ici auxinterfaces aqueuses (110)-Co3O4 et (0001)-CoO(OH) en adoptant une nouvelleapproche de métadynamique d'échantillonnage amélioré, capable d'identifieret caractériser les mécanismes de réaction chimique et d'intégrer pleinement lerôle des degrés de liberté du solvant, permettant ainsi de dévoiler des réactivités chimiques d'une complexité remarquable. L'énergétique, la cinétique et la thermodynamique derrière l'OER sont donc trouvées à ces surfaces d'oxyde de cobalt à l'interface avec l'eauIn this thesis, DFT-MD simulations, coupled with state-of-the-art metadynamics techniques, are applied to gain a global understanding of Co3O4 and CoO(OH) cobalt oxide aqueous interfaces in catalyzing the oxygen evolution reaction (OER), and hence possibly help in the design of novel catalysts basedon non-precious materials, a current key field of research in science and technology, especially of importance for the hydrogen economy, for green technology in a period of time with an ever more growing demand in green-energy. In this thesis, we step-by-step reveal the OER mechanisms on spinel Co3O4 andCoO(OH) cobalt aqueous electrocatalysts carefully and rationally via novelmetadynamics techniques.Up to now, the literature has never taken into account the atomistic modifications on the electrode structure as well as on the interfacial water into their modeling of OER processes. Such lack of knowledge clearly represents a significant hurdle toward the development of improved catalysts, which couldbe overcome by employing methods able to track the catalytic features of theOER at the atomistic scale. For the first time, we show how important itis to take into consideration the presence of the liquid water environment inthe structural characterization of catalyst surfaces, i.e. for (110)-Co3O4 and(0001)-CoO(OH) in this work. A detailed characterization of chemical andphysical properties of the aqueous interfaces is provided (i.e. structure, dynamics, spectroscopy, electric field), for the (110)-Co3O4 and (0001)-CoO(OH)aqueous surfaces.A study of the OER is presented not only by looking at the catalysts, butalso by addressing the role of the water environment in the catalytic process,not done before in literature. Accordingly, both gas-phase and liquid-phaseOER are here investigated at the (110)-Co3O4 and (0001)-CoO(OH) adoptinga novel enhanced sampling metadynamics approach able to address a widerange of chemical reaction mechanisms and to fully include the role of thesolvent degrees of freedom, allowing to unveil reaction networks of remarkablecomplexity. The energetics, kinetics and thermodynamics behind the OER aretherefore found at these cobalt oxide surfaces
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Hayward, Kathryn. "Evolution of asperity contacts during shear failure on frictional interfaces: implications for the initiation of crustal earthquakes." Phd thesis, 2021. http://hdl.handle.net/1885/247348.
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Fault zones and associated slip play a key role in the development of structures within the Earth's upper crust. Fault activity controls crustal-scale fluid flow and fault movement is crucial in the accommodation of strain. Although fault slip is broadly classified as brittle-frictional deformation, there is much we do not understand about the physical mechanisms controlling frictional strength, especially under the extreme conditions accompanying earthquake rupture. This thesis presents the results of five experimental studies. These complementary studies have sought to answer fundamental questions about dynamic frictional processes, including 1) how the structure and properties of materials on the fault interface changes with the application of high strain rates and normal stresses during fault slip; and 2) how slip-induced changes in interface properties modify the strength and behaviour of faults. Experimental results are underpinned by the parallel development of a new interferometry-based displacement sensor and the synchronous acquisition of fault strain data. Experiments have been undertaken on a Paterson triaxial apparatus, focusing on SiO2, both in its crystalline (quartz) and amorphous (fused quartz) forms. Results show that over time scales of less than one millisecond and displacements of tens of microns, significant changes occur in the structure of materials on fault interfaces. At high normal stresses and slip velocities less than ~ 0.05 ms-1, the crystalline structure of the quartz partially lost though the process of mechanical amorphization. At higher slip velocities > 0.05 ms-1, enough heat is generated to melt quartz. However, the onset of amorphization or melting does not necessarily drive fault weakening; the amorphous layer must reach temperatures sufficient to cross the kinematic threshold referred to as the 'glass transition' to allow strain to be accommodated through viscous shearing. When melted regions quench at the end of slip, they can weld the fault surfaces together, instantaneously increasing the cohesive strength and changing conditions necessary to reactivate the fault. The molecular structure of these melt-welded regions is shown to be altered to a densified form, resulting from both the rapid cooling rates and exposure to very high pressures. Synchronised data acquisition allows measurement of both the onset of fault rupture and sample shortening resulting from fault slip. Contrary to assumptions made in many previous studies, experimental fault slip differs from natural earthquake slip, with the former occurring only after the entire surface has ruptured. The synchronised sensors also detect the passage of elastic waves propagating from the rupture and reflecting withing the loading assembly. As the waves pass through the sample, they momentarily change the stress conditions on the fault, potentially enhancing slip or contributing to arrest. These results highlight how technological advances have given us a new understanding of the link between mechanical and microstructural processes, while underscoring the underlying link between sample and apparatus behaviour. In the future, these developments will allow us to explore the fundamental physics of fault slip, which in turn, can be applied to macroscopic understanding of the earthquake cycle and the evolution of fault rupture.
Books on the topic "Contact interface evolution"
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Faucher, Luc, and Pierre Poirier. Mother Culture, Meet Mother Nature. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199367511.003.0017.
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Research on the adaptive characteristics of the human immune system reveals that evolutionary algorithms are not strictly matters of replication. And research in genomics suggests that there is no a single source of evolutionary information that carries the same content in every environment. A plausible theory of cultural evolution must acknowledge the possibility that multiple selective algorithms are operating at different time-scales, on different units of selection, with different logical structures; but it must explain how different selective processes are interfaced to yield culturally stable phenomena. This paper advances an empirically plausible approach to memetics that recognizes a wider variety of evolutionary algorithms; and it advances a pluralistic approach to cultural change. Finally, it shows that multiple forms of processing, operating at different timescales, on different units of selection, collectively sustain the human capacity to form and use certain types of representations.
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Ruxton, Graeme D., William L. Allen, Thomas N. Sherratt, and Michael P. Speed. Dazzle camouflage. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199688678.003.0013.
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Dazzle camouflage is a putative anti-predator adaptation that works to reduce predation by camouflaging movement itself, comprising coloration that interferes with predator perception of prey speed and trajectory. Accurately estimating speed and trajectory is essential for any predator that needs to know where its prey is likely to be in the near future so that it can position itself to intercept. The dazzle hypothesis is that prey coloration can interfere with these judgements. Experimental support for dazzle camouflage is currently very mixed, and we are not yet clear whether dazzle effects occur in natural systems. Here we first discuss illustrative examples of putative disruptive effects in biological and military design. Then we identify where firm and less firm conclusions can be made on the role of pattern contrast, pattern orientation, and internal object motion, before moving on to consider the evolution and ecology of dazzle camouflage.
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Meier, Dennis, Jan Seidel, Marty Gregg, and Ramamoorthy Ramesh. Domain Walls. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198862499.001.0001.
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Technological evolution and revolution are both driven by the discovery of new functionalities, new materials and the design of yet smaller, faster, and more energy-efficient components. Progress is being made at a breathtaking pace, stimulated by the rapidly growing demand for more powerful and readily available information technology. High-speed internet and data-streaming, home automation, tablets and smartphones are now ‘necessities’ for our everyday lives. Consumer expectations for progressively more data storage and exchange appear to be insatiable. In this context, ferroic domain walls have attracted recent attention as a completely new type of oxide interface. In addition to their functional properties, such walls are spatially mobile and can be created, moved, and erased on demand. This unique degree of flexibility enables domain walls to take an active role in future devices and hold a great potential as multifunctional 2D systems for nanoelectronics. With domain walls as reconfigurable electronic 2D components, a new generation of adaptive nano-technology and flexible circuitry becomes possible, that can be altered and upgraded throughout the lifetime of the device. Thus, what started out as fundamental research, at the limit of accessibility, is finally maturing into a promising concept for next-generation technology.
Book chapters on the topic "Contact interface evolution"
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Boinovich, Ludmila, and Alexandre Emelyanenko. "Characterizing the Physicochemical Processes at the Interface through Evolution of the Axisymmetric Droplet Shape Parameters." In Advances in Contact Angle, Wettability and Adhesion, 99–129. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119459996.ch4.
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Chang, Chia-Hu, and Ja-Ling Wu. "Evolution-based Virtual Content Insertion with Visually Virtual Interactions in Videos." In Multimedia Interaction and Intelligent User Interfaces, 163–84. London: Springer London, 2010. http://dx.doi.org/10.1007/978-1-84996-507-1_7.
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Fouse, Adam, Ryan S. Mullins, Gabriel Ganberg, and Chad Weiss. "The Evolution of User Experiences and Interfaces for Delivering Context-Aware Recommendations to Information Analysts." In Advances in Intelligent Systems and Computing, 15–26. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60492-3_2.
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Schmickler, Wolfgang. "The metal-solution interface." In Interfacial Electrochemistry. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195089325.003.0008.
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The interface between a metal and an electrolyte solution is the most important electrochemical system, and we begin by looking at the simplest case, in which no electrochemical reactions take place. The system we have in mind consists of a metal electrode in contact with a solution containing inert, nonreacting cations and anions. A typical example would be the interface between a silver electrode and an aqueous solution of KF. We further suppose that the electrode potential is kept in a range in which no or only negligible decomposition of the solvent takes place - in the case of an aqueous solution, this means that the electrode potential must be below the oxygen evolution and above the hydrogen evolution region. Such an interface is said to be ideally polarizable, a terminology based on thermodynamic thinking. The potential range over which the system is ideally polarizable is known as the potential window, since in this range electrochemical processes can be studied without interference by solvent decomposition. As we pointed out in the introduction, a double layer of equal and opposite charges exists at the interface. In the solution this excess charge is concentrated in a space-charge region, whose extension is the greater the lower the ionic concentration. The presence of this spacecharge region entails an excess (positive or negative) of ions in the interfacial region. In this chapter we consider the case in which this excess is solely due to electrostatic interactions; in other words, we assume that there is no specific adsorption. This case is often difficult to realize in practice, but is of principal importance for understanding more complicated situations. A simple but surprisingly good model for the metal-solution interface was developed by Gouy and Chapman as early as 1910. The basic ideas are the following: The solution is modeled as point ions embedded in a dielectric continuum representing the solvent; the metal electrode is considered as a perfect conductor. The distribution of the ions near the interface is calculated from electrostatics and statistical mechanics.
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Gleghorn, Gregory D., and Alan Harper. "Logistics and Supply Chain Management and the Impact of Information Systems and Information Technology." In Advances in Business Information Systems and Analytics, 295–301. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-6473-9.ch014.
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Supply chain management is the backbone of the movement of goods and services. Supply chain management is a term that has evolved from logistics. Traditional supply chain management involved a salesperson, who was the focal point in the supply or logistical chain. In a traditional supply chain model, a business would contact a salesperson to inquire about a product or a salesperson would pitch a product to a business; then the ordering process or supply chain management of movement of goods would funnel through the salesperson as the initial interface. Today, the supply chain has evolved; IT has changed the landscape of the supply chain with applications, such as RFID (Radio Frequency Identification), CRM (Customer Relationship Management systems), and ERP (Enterprise Resource Programs). The result is major changes in competitiveness, efficiency, costs, and strategy. This chapter examines the evolution of supply chain management and the impact of IT.
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Gupta, Manish, and Rui Chen. "Understanding Evolution of Virtual Worlds Research." In User Interface Design for Virtual Environments, 16–40. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-61350-516-8.ch002.
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Virtual worlds are emerging as important socio-technical artifacts in contemporary society. Improvements in technology – both hardware and software performance and costs – have facilitated fast emergence of complex and near-real experience virtual worlds. Recent years have seen an unprecedented growth in number of users and corporations joining these virtual worlds. They have enabled unique business models in the digital economy and cast far-reaching impacts on the society spanning literature to leisure. The chapter analyzes 106 journal articles published in last decade to uncover a shift in focus of research on different aspects of virtual worlds. The chapter identifies six dominant themes of research on virtual worlds and then content-analyzes extant literature to show how these themes have emerged in research on virtual worlds. This presents unique insights into perceived relative importance of impact of different aspects of virtual worlds on individuals and organizations alike.
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Shaw, Jo. "Citizenship: Contrasting Dynamics at the Interface of Integration and Constitutionalism." In The Evolution of EU Law, 608–50. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192846556.003.0019.
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This chapter explores the complex tapestry of citizenship in the European Union context, and examines how discourses of citizenship illuminate both the nature of European integration and the process of gradual constitutionalization. The intention is to re-evaluate the role played by citizenship in the evolving processes of Union polity-formation, and the connection between citizenship and the various dynamics of constitution-making. The chapter has three substantive sections which examine the complex and dynamic relationship between citizenship of the Union, the free movement dynamics underpinning EU law, and concepts of citizenship in a wider constitutional context. The chapter finds that there is a tension between citizenship of the Union, as part of the EU’s ‘old’ incremental constitutionalism based on the constitutionalization of the existing Treaties, and citizenship in the Union, where the possibilities of a ‘new’ constitutionalism based on renewed constitutional documents have yet to be fully realized.
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Rodrigues de Oliveira, Renan, Fábio Moreira Costa, Cedric Luiz de Carvalho, and Ana Paula Ambròsio. "Semantic Retrieval of Documents from Digital Repositories and Twitter Integration in the Moodle Environment." In Artificial Intelligence Technologies and the Evolution of Web 3.0, 37–65. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-8147-7.ch003.
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Virtual learning environments represent an important step in enabling distance and blended education. Moodle's structure for content enables the identification of well-defined learning contexts. Nevertheless, Moodle currently does not provide standard features to leverage the use of such contextual information, nor does it provide a standard built-in search facility. This chapter presents a context-sensitive Moodle plug-in for the search of external resources that allows semantic-based retrieval of documents from any external repository that offers an OAI-PMH standard compliant interface. As a way to increase their potential use, the plug-in also retrieves Twitter messages (known as tweets), since social networks are shown as an important tool to support education. Retrieved resources are presented in order of importance according to both the query terms provided by the user and the current context derived from the Moodle content structure. Searches are semantically expanded by evaluating the query terms according to a specific ontology associated with the context.
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AJAEV, VLADIMIR S., and STEPHEN H. DAVIS. "INFLUENCE OF CONTACT-ANGLE CONDITIONS ON EVOLUTION OF SOLIDIFICATION FRONTS." In Interfaces for the 21st Century: New Research Directions in Fluid Mechanics and Materials Science, 233. PUBLISHED BY IMPERIAL COLLEGE PRESS AND DISTRIBUTED BY WORLD SCIENTIFIC PUBLISHING CO., 2002. http://dx.doi.org/10.1142/9781860949609_0017.
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Cubo, Javier, and Ernesto Pimentel. "Reusing Services through Context-Aware Discovery and Adaptation in Pervasive Systems." In Software Design and Development, 1956–2013. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4301-7.ch092.
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Reusing of software entities, such as components or services, to develop software systems has matured in recent years. However, it has not become standard practice yet, since using pre-existing software requires the selection, composition, adaptation, and evolution of prefabricated software parts. Recent research approaches have independently tackled the discovery, composition, or adaptation processes. On the one hand, the discovery process aims at discovering the most suitable services for a request. On the other hand, the adaptation process solves, as automatically as possible, mismatch cases which may be given at the different interoperability levels among interfaces by generating a mediating adaptor based on an adaptation contract. In this chapter, the authors present the DAMASCo framework, which focuses on composing services in mobile and pervasive systems accessed through their public interfaces, by means of context-aware discovery and adaptation. DAMASCo has been implemented and evaluated on several examples.
Conference papers on the topic "Contact interface evolution"
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Peng, Wei, James Kiely, and Yiao-Tee Hsia. "Wear Analysis of Head-Disk Interface During Contact." In ASME/STLE 2004 International Joint Tribology Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/trib2004-64050.
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To achieve a higher storage density in a hard disk drive, the fly height of the air bearing slider, as part of the magnetic spacing, has to be minimized. At an ultra-low fly height, the intermittent / continuous contact at the head–disk interface (HDI) is unavoidable and directly affects the mechanical and magnetic performance of the hard disk drive, and is of great interest. The HDI wear has a non-linear and time-varying nature due to the change of contact force and roughness. To predict the HDI wear evolution, an iterative model of Coupled Head And Disk (CHAD) wear, is developed based on the contact mechanics. In this model, a composite transient wear coefficient is adopted and multiple phases of the wear evolution are established. A comprehensive contact stiffness is derived to characterize the contact at the HDI. The abrasive and adhesive wear is calculated based on the extended Archard’s wear law. The plastic and elastic contact areas are calculated with a 3-D sliding contact model. Based on the CHAD wear model, for the first time, the coupling between head and disk wear evolutions is thoroughly investigated. Accelerated wear tests have also been performed to verify the disk wear effect on the slider wear. A wear coefficient drop with time is observed during the tests and it is attributed to a wear mechanism shift from abrasive to adhesive wear. A shift in the type of contact from plastic to elastic accounts for the wear mechanism change.
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Zhang, Song, Lili Zheng, and Hui Zhang. "Microstructure Evolution and Bond Formation at the Contact Interface During Ultrasonic Consolidation Process." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37203.
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In this paper a cellular automata-finite elements (CAFE) model is developed by combining traditional finite elements (FE) model and cellular automata (CA) model. The microstructure under different process conditions of ultrasonic consolidation (UC) process for Al 7075 is studied. It is found that higher energy input process conditions (higher applied load and sonotrode oscillation amplitude, lower sonotrode travel speed) will lead to a higher value of dynamic recrystallization (DRX) fraction for UC deposited foils. The mean dislocation density of the UC deposited material will increase with the applied load while it decreases with the increase of sonotrode travel speed and oscillation amplitude.
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Madhavan, V., S. Chandrasekar, and T. N. Farris. "Direct Observations of the Chip-Tool Interface in Machining." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1134.
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Abstract An experimental study has been made of the chip-tool interface and its evolution in the low speed cutting of metals. Specially prepared transparent glass and sapphire tools have been used to cut commercially pure metals such as lead, aluminium and copper. The chip-tool interface has been observed in situ using optical microscopy and recorded on film and video tape. By observing the motion of inhomogeneities in the chip, and pro-filometry of the chip and tool surfaces, it has been established that there is intimate sliding contact between the chip and the tool at and near the cutting edge. Farther away from the cutting edge and close to the end of the chip-tool contact, metal transfer and sticking are observed between the chip and tool surfaces. It has been shown that metal deposition on the tool rake surface initially occurs near the end of contact and progressively extends outward and away from the cutting edge as the length of contact increases. The sticking and sliding zones are unchanged when these pure metals are machined with tungsten carbide tools.
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Lin, Enqiang, Qiyong Chen, Ozan C. Ozdemir, Sinan Müftü, and Victor K. Champagne. "Effects of Interface Bonding on the Residual Stresses in Cold Sprayed Al-6061: A Numerical Investigation." In ITSC2018, edited by F. Azarmi, K. Balani, H. Li, T. Eden, K. Shinoda, T. Hussain, F. L. Toma, Y. C. Lau, and J. Veilleux. ASM International, 2018. http://dx.doi.org/10.31399/asm.cp.itsc2018p0278.
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Abstract A contact model that accounts for interfacial cohesion and thermal conduction is developed to investigate the influence of bonding on the final residual stresses build-up in cold spray. The residual stress evolution in the cold sprayed Al-6061 coating on an Al-6061 substrate is investigated via three-dimensional (3D) single-particle and multi-particle impact simulations. It is shown that the interface bonding mainly affects the local residual stress distribution near the interfaces. The residual stresses are largely due to the kinetic peening and bonding effects. The thermal cooling has negligible influence. In general, the peening effect introduces a compressive stress while the bonding effect results in a relaxation to this compressive stress. This work suggests that the interface bonding should be considered as one of the essential factors in numerical modeling of the residual stresses evolution in cold spray.
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Chauda, Gaurav, and Daniel J. Segalman. "Some Exploration of the Path-Dependence in the Contact Analysis." In ASME 2020 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/detc2020-22439.
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Abstract One of the most frustrating features of joint mechanics is that all the important processes take place precisely where they cannot be seen or measured directly — the interface between contacting bodies. In order to achieve some insight into the mechanisms that give rise to the nonlinearities of joints one naturally turns to analytic or numerical models of interface mechanics. With such models, one can explore the significance of different assumptions of kinematics or surface mechanics and compare those with laboratory experiments on the integrated joints. Among the limitations of such modeling strategies are the twin problems of 1) employing suitable models for friction and 2) solving the resulting equations. There is evidence that the commonly used Coulomb friction model is inconsistent with the experimentally observed behavior of lap joints; it is necessary to explore the use of more complex models. Additionally, even when computing contact and sliding with the relatively simple Coulomb friction model, capturing the evolution of traction fields from one load set to the next in a physically plausible manner has been a continuing challenge. Obtaining fidelity to such path dependence for more complex models would be consequently more difficult. This issue has motivated the research reported here on the source of the difficulty in modeling path-dependent contact and possible solutions. A two-parameter Coulomb friction model is used to test a conventional contact algorithm and a newer one devised specifically to capture path dependence correctly. The evolution of lateral traction during cyclic loading is used to illustrate how the shear traction distribution at each load step evolves from that of the previous.
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Dwivedi, S. K., and H. D. Espinosa. "Modeling Intersonic Crack Propagation in Fiber Reinforced Composites With Contact/Cohesive Laws." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/ad-25313.
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Abstract Dynamic crack propagation in an unidirectional Carbon/Epoxy composite is studied through finite element analyses in total Lagrangian co-ordinates. A finite deformation anisotropic visco-plastic model is used to describe the constitutive response of the composite. Crack initiation and propagation is simulated by embedding zero thickness interface element along the possible crack path. An irreversible cohesive law is used to describe the evolution of normal and shear tractions as a function of displacement jumps. The compressive response prior to interface failure is analyzed using contact impenetrability conditions. The failure of the first interface element at the pre-notch tip models crack initiation. Crack propagation is modeled through consecutive failure of interface elements. Dynamic crack propagation phenomena are studied in terms of crack initiation time, crack speed, mode I and mode II displacement jumps and tractions associated with the failure of interface elements, effective plastic strain at the crack tip and path independent integral J′. Analyses are first carried out for the dynamic crack propagation along bi-material interfaces. The results obtained from present analyses agree well with literature data. Detailed analyses are carried out for a pre-notched unidirectional Carbon/Epoxy composite material. The impact velocity in the analyses is an imposed velocity over an assumed impact region and remains constant throughout the analysis. Analyses are carried out at impact velocities of 5, 10, 20, 30 and 40 m/s, assuming the crack wake is frictionless. Moreover, analyses at impact velocities of 30 and 40 m/s are also carried out with a friction coefficient of 0.5 along the crack surfaces. The analyses established intersonic crack speed in the fiber reinforced composite material. Intersonic crack propagation for the impact velocities of 40 m/s is 400% of the shear wave speed and 87% of the longitudinal wave speed. Detailed discussion is given on the features of sub-sonic and intersonic crack propagation in Carbon/Epoxy composite materials. It is shown that the friction coefficient along the crack surface plays an important role by smearing the discontinuous field that develops behind the crack tip and by reducing crack speed in the intersonic regime. The analyses show that the contour integral J′ computed at near field contours are path independent and can serve as a parameter for characterizing intersonic crack propagation.
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Yd, Sumith, and Shalabh C. Maroo. "A New Algorithm for Contact Angle Estimation in Molecular Dynamics Simulations." In ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icnmm2015-48569.
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It is important to study contact angle of a liquid on a solid surface to understand its wetting properties, capillarity and surface interaction energy. While performing transient molecular dynamics (MD) simulations it requires calculating the time evolution of contact angle. This is a tedious effort to do manually or with image processing algorithms. In this work we propose a new algorithm to estimate contact angle from MD simulations directly and in a computationally efficient way. This algorithm segregates the droplet molecules from the vapor molecules using Mahalanobis distance (MND) technique. Then the density is smeared onto a 2D grid using 4th order B-spline interpolation function. The vapor liquid interface data is estimated from the grid using density filtering. With the interface data a circle is fitted using Landau method. The equation of this circle is solved for obtaining the contact angle. This procedure is repeated by rotating the droplet about the vertical axis. We have applied this algorithm to a number of studies (different potentials and thermostat methods) which involves the MD simulation of water.
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Shen, Shengnan, Hui Li, Fuhao Cui, Guoqing Zhang, and Xiangyu Dai. "Contact Modeling of Traveling Wave Ultrasonic Motors." In ASME 2014 Conference on Information Storage and Processing Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/isps2014-6985.
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In the pursuit of high areal recording density towards 10 Tb/in2, it is necessary to improve the positioning accuracy of the magnetic head in the hard disk drive head-positioning control system. Ultrasonic motors (USMs) are novel electric motors used for positioning controls. Due to the drive characteristic of USMs, wear and fatigue of friction material at the contact friction interface are inevitable. Contact deformation can cause local damage of USMs. Therefore, obtaining the details of the stress distribution in the friction material due to the inelastic deformation is important. In this work, a contact model of traveling wave ultrasonic motor (TWUSM) is proposed. A three dimensional finite element model with cohesive zone elements embedded between friction material and rotor is then developed. Infinite finite elements are incorporated in this modeling as the boundary condition as the model thickness is typically many orders smaller than the longitudinal dimension. The evolution of deformation in friction material and rotor due to the mechanical surface loading is presented. The possible interfacial delamination process between friction material and rotor is numerically studied. And the friction coefficient effect of the friction material on the delamination propagation is also investigated.
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Goryacheva, I. G. "Modelling the Wear Process of Inhomogeneous Bodies." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63494.
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The approaches of contact mechanics are used to evaluate the evolution of the contact characteristics in wear process of inhomogeneous bodies (coated bodies, two-phase composition, bodies with inclusions, etc.). The mathematical model is formulated and used to study the kinetics of the wear process depending on the parameters of inhomogeneity such as size and density of inclusions, waviness at the coating-substrate interface, local hardening parameters, etc.
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Gao, Bo, and Xiaofeng Peng. "Coupling Effect of Interfacial Transport on Particle-Surface Capillary Forces." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52033.
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In this investigation, an interest is addressed on getting some fundamental insights on the theoretical analysis of inter-particle forces and interfacial evaporation induced by the existence of liquid at pore level. The imbalance of capillary attractive forces and great potential of heat/mass transport at interfaces are found to be most important in driving the dynamic evolution of the system. Connected by micro liquid layer lying among particle(s) and supporting plate, the particle-surface system can experience both repulsion and attraction interactions. Based on the theoretical model proposed in current investigation, the particle’s mechanical status is found to be closely dependent on particle-surface distance, contact line radius, contact properties and mean curvature of the interface. Meanwhile, geometrical information and governing equations bridge interfacial transport together with possible particle movements.
Reports on the topic "Contact interface evolution"
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Lever, James, Susan Taylor, Arnold Song, Zoe Courville, Ross Lieblappen, and Jason Weale. The mechanics of snow friction as revealed by micro-scale interface observations. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42761.
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The mechanics of snow friction are central to competitive skiing, safe winter driving and efficient polar sleds. For nearly 80 years, prevailing theory has postulated that self-lubrication accounts for low kinetic friction on snow: dry-contact sliding warms snow grains to the melting point, and further sliding produces meltwater layers that lubricate the interface. We sought to verify that self-lubrication occurs at the grain scale and to quantify the evolution of real contact area to aid modeling. We used high-resolution (15 μm) infrared thermography to observe the warming of stationary snow under a rotating polyethylene slider. Surprisingly, we did not observe melting at contacting snow grains despite low friction values. In some cases, slider shear failed inter-granular bonds and produced widespread snow movement with no persistent contacts to melt (μ < 0.03). When the snow grains did not move and persistent contacts evolved, the slider abraded rather than melted the grains at low resistance (μ < 0.05). Optical microscopy revealed that the abraded particles deposited in air pockets between grains and thereby carried heat away from the interface, a process not included in current models. Overall, our results challenge whether self-lubrication is indeed the dominant mechanism underlying low snow kinetic friction.
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Lever, James, Susan Taylor, Garrett Hoch, and Charles Daghlian. Evidence that abrasion can govern snow kinetic friction. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42646.
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The long-accepted theory to explain why snow is slippery postulates self-lubrication: frictional heat from sliding melts and thereby lubricates the contacting snow grains. We recently published micro-scale interface observations that contradicted this explanation: contacting snow grains abraded and did not melt under a polyethylene slider, despite low friction values. Here we provide additional observational and theoretical evidence that abrasion can govern snow kinetic friction. We obtained coordinated infrared, visible-light and scanning-electron micrographs that confirm that the evolving shapes observed during our tribometer tests are contacting snow grains polished by abrasion, and that the wear particles can sinter together and fill the adjacent pore spaces. Furthermore, dry-contact abrasive wear reasonably predicts the evolution of snow-slider contact area and sliding-heat-source theory confirms that contact temperatures would not reach 0°C during our tribometer tests. Importantly, published measurements of interface temperatures also indicate that melting did not occur during field tests on sleds and skis. Although prevailing theory anticipates a transition from dry to lubricated contact along a slider, we suggest that dry-contact abrasion and heat flow can prevent this transition from occurring for snow-friction scenarios of practical interest.
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Izhar, Shamay, Maureen Hanson, and Nurit Firon. Expression of the Mitochondrial Locus Associated with Cytoplasmic Male Sterility in Petunia. United States Department of Agriculture, February 1996. http://dx.doi.org/10.32747/1996.7604933.bard.
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The main goal of the proposed research was to continue the mutual investigations into the molecular basis of CMS and male fertility restoration [MRF], with the ultimate goal of understanding these phenomena in higher plants. The experiments focused on: (1) dissecting apart the complex CMS - specific mitochondrial S-Pcf locus, in order to distinguish its essential parts which cause sterility from other parts and study its molecular evolution. (2) Studying the expression of the various regions of the S-Pcf locus in fertile and sterile lines and comparing the structure and ultrastructure of sterile and fertile tissues. (3) Determine whether alteration in respiration is genetically associated with CMS. Our mutual investigations further substantiated the association between the S-Pcf locus and CMS by the findings that the fertile phenotype of a population of unstable petunia somatic hybrids which contain the S-Pcf locus, is due to the presence of multiple muclear fertility restoration genes in this group of progenies. The information obtained by our studies indicate that homologous recombination played a major role in the molecular evolution of the S-Pcf locus and the CMS trait and in the generation of mitochondrial mutations in general. Our data suggest that the CMS cytoplasm evolved by introduction of a urs-s containing sublimon into the main mitochondrial genome via homologous recombination. We have also found that the first mutation detected so far in S-Pcf is a consequence of a homologous recombination mechanism involving part of the cox2 coding sequence. In all the cases studied by us, at the molecular level, we found that fusion of two different cells caused mitochondrial DNA recombination followed by sorting out of a specific mtDNA population or sequences. This sequence of events suggested as a mechanism for the generation of novel mitochondrial genomes and the creation of new traits. The present research also provides data concerning the expression of the recombined and complex CMS-specific S-Pcf locus as compared with the expression of additional mitochondrial proteins as well as comparative histological and ultrastructural studies of CMS and fertile Petunia. Evidence is provided for differential localization of mitochondrially encoded proteins in situ at the tissue level. The similar localization patterns of Pcf and atpA may indicate that Pcf product could interfere with the functioning of the mitochondrial ATPase in a tissue undergoing meiosis and microsporogenesis. Studies of respiration in CMS and fertile Petunia lines indicate that they differe in the partitioning of electron transport through the cytochrome oxidase and alternative oxidase pathways. The data indicate that the electron flux through the two oxidase pathways differs between mitochondria from fertile and sterile Petunia lines at certain redox states of the ubiquinone pool. In summary, extensive data concerning the CMS-specific S-Pcf locus of Petunia at the DNA and protein levels as well as information concerning different biochemical activity in CMS as compared to male fertile lines have been accumulated during the three years of this project. In addition, the involvement of the homologous recombination mechanism in the evolution of mt encoded traits is emphasized.