The Phonon Dissipation Mode in Nanofriction

2016 ◽  
Author(s):  
Zaoqi Duan ◽  
Shuang Cai ◽  
Yan Zhang ◽  
Yunfei Chen ◽  
Yun Dong
Keyword(s):  
Simulation Modeling ◽  
Md Simulation ◽  
Influence Factor ◽  
Atomic Scale ◽  
Sliding Velocity ◽  
Graphene Flake ◽  
Active Control Of Friction ◽  
Densities Of States ◽  
The Relationship ◽  
Special Frequencies

The phonon dissipation is investigated through molecular dynamics (MD) simulation modeling graphene flake sliding on supported graphene in this paper. With the help of the advantage of MD, we explore the phonon mode variation of the substrate induced by the behavior of friction in terms of phonon densities of states. Moreover, phonon dissipation modes connected with the relative sliding velocity and the temperature of system are established respectively. The simulation results demonstrate phonon dissipation is represented as special phonon frequencies while those are closely related to the sliding velocities but would not shift as the change of temperatures. For an explanation of the special frequencies, we further simplify the model by directly adding the velocity to the atoms of the flake in the MD model, although it is impractical. It is found that a special frequency of phonon dissipation is generally in agreement with the sliding frequency at low temperature eliminating the interference of temperature in a range of velocities from 50m/s to 250m/s, namely, the velocity is directly related to the modes of phonon dissipation and friction, which is consistent with the previously reported result[1] that the velocity is an influence factor for friction both in experimental and theoretical researches. Therefore, the relationship makes possible the active control of friction. It is the first step toward using this method to reveal the fundamental questions in the study of atomic-scale friction.

scholarly journals Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

2014 ◽  
Vol 20 (6) ◽  
pp. 1782-1790 ◽  
Author(s):  
Ping Lu ◽  
Eric Romero ◽  
Shinbuhm Lee ◽  
Judith L. MacManus-Driscoll ◽  
Quanxi Jia
Keyword(s):  
Atomic Scale ◽  
Specimen Thickness ◽  
Peak Width ◽  
Thin Specimen ◽  
Gaussian Peak ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Relationship ◽  
Chemical Quantification

AbstractWe report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). With thin specimen conditions and localized EDS scattering potential, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak width are investigated using SrTiO3 (STO) as a model specimen. The relationship between the peak width and spatial resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study cation occupancy in a Sm-doped STO thin film and antiphase boundaries (APBs) present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the APBs likely owing to the effect of strain.

scholarly journals Influence factor of consumers interest on using E-money

2019 ◽  
Vol 3 (2) ◽  
pp. 176-186
Author(s):  
Ni Wayan Mentari ◽  
I Nyoman Djinar Setiawina ◽  
I Made Kembar Sri Budhi ◽  
I Wayan Sudirman
Keyword(s):  
Influence Factor ◽  
Consumer Attitudes ◽  
Structural Equations ◽  
Partial Least Square ◽  
Least Square ◽  
Coefficient Of Determination ◽  
Consumer Knowledge ◽  
Perceived Benefits ◽  
Consumer Interest ◽  
The Relationship

The objectives of this study was to determine the factors that influence consumer interest in using e-money in Badung and Denpasar City in Bali. This study uses the analysis of SEM structural equations with alternative Partial Least Square (PLS). Consumer attitudes mediate the influence of the relationship between perceived benefits and perceived ease of consumer interest in using e-money, the attitude of consumers in using e-money does not mediate the effect of the relationship between customer knowledge on consumer interest in using e-money. The coefficient of determination R-square for attitude variables is 0.502, which means that the variable attitude of consumers in using e-money can be explained by the variable perception of benefits, perceived convenience and consumer knowledge by 50.2 percent, or in other words, every variant of consumer attitudes e-money will be explained by the variable perception of benefits, perceived ease and consumers knowledge by 50.2 percent, the rest explained by other variables outside the model by 49.8 percent.

Numerical study of silicon vacancy color centers in silicon carbide by helium ion implantation and subsequent annealing

2021 ◽  
Author(s):  
Yexin Fan ◽  
ying song ◽  
zongwei xu ◽  
jintong wu ◽  
rui zhu ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Ion Implantation ◽  
Color Center ◽  
Md Simulation ◽  
Subsequent Annealing ◽  
Atomic Scale ◽  
New Method ◽  
Color Centers ◽  
Silicon Vacancy ◽  
Helium Ion

Abstract Molecular dynamics (MD) simulation is adopted to discover the underlying mechanism of silicon vacancy color center and damage evolution during helium ions implanted four-hexagonal silicon carbide (4H-SiC) and subsequent annealing. The atomic-scale mechanism of silicon vacancy color centers in the process of He ion implantation into 4H-SiC can be described more accurately by incorporating electron stopping power for He ion implantation. We present a new method for calculating the silicon vacancy color center numerically, which considers the structure around the color center and makes the statistical results more accurate than the Wigner-Seitz defect analysis method. At the same time, photoluminescence (PL) spectroscopy of silicon vacancy color center under different helium ion doses is also characterized for validating the numerical analysis. The MD simulation of the optimal annealing temperature of silicon vacancy color center is predicted by the proposed new method.

scholarly journals Atomic-Scale Hydration Structures on a Heterogeneously Charged Surface Revealed by FM-AFM and MD Simulation

2018 ◽  
Vol 61 (6) ◽  
pp. 378-383
Author(s):  
Kenichi UMEDA ◽  
Lidija ZIVANOVIC ◽  
Kei KOBAYASHI ◽  
Peter SPIJKER ◽  
Adam S. FOSTER ◽  
...  
Keyword(s):  
Md Simulation ◽  
Atomic Scale ◽  
Charged Surface

The Analysis of the Load Rate Influence Factors Based on the Grey Correlation

2014 ◽  
Vol 631-632 ◽  
pp. 94-98
Author(s):  
Xue jun Wang ◽  
Ji Xiang Zhang ◽  
Zhen Gao Zhang ◽  
Ming Zhi Liu
Keyword(s):  
Influence Factor ◽  
Rapid Development ◽  
Influence Factors ◽  
Key Factors ◽  
Grey Correlation ◽  
Power Characteristics ◽  
Load Rate ◽  
Grey Correlation Analysis ◽  
Influence Degree ◽  
The Relationship

With the rapid development of power industry, the load rate which describes the power characteristics is playing a more and more important role, this paper uses the grey correlation analysis to find the relationship between the load rate and the influence factors based on the historical data of the load rate influence factors and analyzes the weight of each influence factor quantitatively through the grey correlation coefficient so as to reflect the influence degree of different factors on load rate, meanwhile, through the analysis of various influencing factors of load rate, this paper hopes to clarify its effects on the load rate which includes strength, size and the order and help the power grid enterprise choose the key factors influencing the load rate which provide a basis for the future to improve the load rate.

Analysis of Carrying Capacity and Friction Torque of Friction Pair Fluid-Film for High Parameter Bellows Mechanical Seal

2013 ◽  
Vol 455 ◽  
pp. 207-211
Author(s):  
Mutellip Ahmat ◽  
Zhi Wei Niu ◽  
Guzaiayi Abudoumijiti
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
Influence Factor ◽  
Friction Pair ◽  
Scientific Basis ◽  
Friction Torque ◽  
Fluid Film ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
The Relationship

The friction pair for bellows mechanical seal as a friction element is one of the key components for it. In this research, by based on the computational fluid dynamics (CFD) numerical theory, using the Fluent software, corresponding model and parameters, the fluid-film between the clearance of the sealing ring friction pair for the bellows mechanical seal under such the high-temperature, high-pressure, high-speed as complex working conditions is numerically simulated, the relationship between the carrying-capacity of the fluid-film and the temperature, the viscosity of the fluid-film, the relationship between friction torque of the fluid-film and the speed, viscosity of the fluid-film, the influence factor of leakage are obtained. The researching results provide the scientific basis for the optimization designing of the high parameter bellows mechanical seals.

A Study on the Correlativity and Date Simulation between Rock Abrastivity and Physical and Mechanical Indexes of Rock in Qingdao Subway, China

2012 ◽  
Vol 476-478 ◽  
pp. 1718-1721 ◽  
Author(s):  
De Hong Jiang ◽  
Li Ming Bian
Keyword(s):  
Test Data ◽  
Influence Factor ◽  
Mathematic Model ◽  
Economic Benefits ◽  
Attrition Rate ◽  
Subway Tunnel ◽  
Tbm Cutter ◽  
Digging Efficiency ◽  
The Relationship ◽  
Main Influence

The attrition rate of a TBM cutter connects with the economic benefits of the TBM application and digging efficiency. The main influence factor of the attrition rate of the TBM cutter is rock abrastivity. The rock abrastivity is in contact with the physical and mechanical indexes of rock and rock attributes. The relationship between the rock abrastivity and the physical and mechanical indexes of rock is studied by experiments and mathematical statistics. The experimental samples are collected in the Qingdao subway tunnel and done rock mechanics room experimentation and rock abrastivity experimentation separately in the lab Based on calculation and analyses of the test data. We obtain a mathematic model describing the relationship between rock abrastivity and physical and mechanical indexes of rock and summarize and interpret the correlativity between them.

A Molecular Dynamics Simulation Study on the Relationship between Hydrogen Bond and Damping Properties of AO-70/NBR Composites

2017 ◽  
Vol 748 ◽  
pp. 29-34 ◽  
Author(s):  
Jing Zhu ◽  
Xiu Ying Zhao ◽  
Meng Song ◽  
Yue Han ◽  
Li Liu ◽  
...  
Keyword(s):  
Md Simulation ◽  
Type A ◽  
Dynamics Simulation ◽  
Butadiene Rubber ◽  
Damping Properties ◽  
Type B ◽  
Fractional Free Volume ◽  
Type C ◽  
Hindered Phenol ◽  
The Relationship

This work was try to study the number and types of hydrogen bonds (H-bonds) formed in hindered phenol AO-70/nitrile butadiene rubber (NBR) composites and their contributions to the damping properties by molecular dynamic (MD) simulation and experimental methods. MD simulation results showed that there were four types of H-bonds, namely, type A (AO-70) –OH...NC– (NBR) H-bonds in AO-70/NBR composites, type B (AO-70) –OH...O=C– (AO-70) H-bonds, type C (AO-70) –OH...OH–(AO-70) and D (AO-70) –OH...O–C– (AO-70) H-bonds, what's more, type A and type B H-Bonds formed more easily than others. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of H-bonds. Meanwhile, the AO-70/NBR composites with AO-70 content of 109 phr had the largest number of H-bonds, smallest fractional free volume (FFV) and resulting in the optimistic damping performance of the composites.

A review on the molecular dynamics simulation of machining at the atomic scale

2001 ◽  
Vol 215 (12) ◽  
pp. 1639-1672 ◽  
Author(s):  
R Komanduri ◽  
L M Raff
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Burr Formation ◽  
Depth Of Cut ◽  
Second Phase ◽  
Nanometric Cutting ◽  
Subsurface Deformation ◽  
Work Material

Molecular dynamics (MD) simulation, like other simulation techniques, such as the finite difference method (FDM), or the finite element method (FEM) can play a significant role in addressing a number of machining problems at the atomic scale. It may be noted that atomic simulations are providing new data and exciting insights into various manufacturing processes and tribological phenomenon that cannot be obtained readily in any other way—theory, or experiment. In this paper, the principles of MD simulation, relative advantages and current limitations, and its application to a range of machining problems are reviewed. Machining problems addressed include: (a) the mechanics of nanometric cutting of non-ferrous materials, such as copper and aluminium; (b) the mechanics of nanometric cutting of semiconductor materials, such as silicon and germanium; (c) the effect of various process parameters, including rake angle, edge radius and depth of cut on cutting and thrust forces, specific force ratio, energy, and subsurface deformation of the machined surface; the objective is the development of a process that is more efficient and effective in minimizing the surface or subsurface damage; (d) modelling of the exit failures in various work materials which cause burr formation in machining; (e) simulation of work materials with known defect structure, such as voids, grain boundaries, second phase particles; shape, size and density of these defects can be varied using MD simulation as well as statistical mechanical or Monte Carlo approaches; (f) nanometric cutting of nanostructures; (g) investigation of the nanometric cutting of work materials of known crystallographic orientation; (h) relative hardness of the tool material with respect to the work material in cutting; a range of hardness values from the tool being softer than the work material to the tool being several times harder than the work material is considered; and (i) the tool wear in nanometric cutting of iron with a diamond tool. The nature of deformation in the work material ahead of the tool, subsurface deformation, nature of variation of the forces and their ratio, and specific energy with cutting conditions are investigated by this method.

Molecular Dynamics Simulation of a Rigid Sphere Indenting a Copper Substrate

2012 ◽  
Author(s):  
Ding Jia ◽  
Longqiu Li ◽  
Andrey Ovcharenko ◽  
Wenping Song ◽  
Guangyu Zhang
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Copper Substrate ◽  
Three Dimensional ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Rigid Sphere ◽  
Displacement Curve ◽  
Loading And Unloading ◽  
Force Displacement

Three-dimensional molecular dynamics (MD) simulation is used to study the atomic-scale indentation process of a spherical diamond tip in contact with a copper substrate. In the indentation simulations, the force-displacement curve is obtained and compared with a modified elastic solution of Hertz. The contact area under different indentation depths is also investigated. The force-displacement curve under different maximum indentation depths is obtained to investigate elastic-plastic deformation during the loading and unloading processes.

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