Rotation-induced axial oscillation of a composite nanoconvertor at low temperature

We propose a model of a nanostructure which can transform an input rotation into an output oscillation. In the model, the rotor has two identical internally hydrogenated deformable parts. The mechanism is that the rotation-induced centrifugal force and van der Waals force drive the recoverable deformation of the hydrogenated deformable parts, which gives rise to the axial translation of the free end of the rotor. Once the two hydrogenated deformable parts deform periodically, the free end of the rotor oscillates periodically in the axial direction. Molecular dynamics simulations are conducted to reveal the dynamic response of the system at low temperature. Four main types of deformation and the first three orders of vibration responses of the hydrogenated deformable parts are analyzed. Synchronous breathing vibration of the two hydrogenated deformable parts produces ideal oscillation with large amplitude. Asynchronous axial vibration of the hydrogenated deformable parts reduces the oscillation amplitude or produces beat vibration. The way to control the amplitude of the axial oscillation/vibration is given.

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Ideal Oscillation of a Hydrogenated Deformable Rotor in a Gigahertz Rotation–Translation Nanoconverter at Low Temperatures

Sensors ◽

10.3390/s20071969 ◽

2020 ◽

Vol 20 (7) ◽

pp. 1969

Author(s):

Bo Song ◽

Jiao Shi ◽

Jinbao Wang ◽

Jianhu Shen ◽

Kun Cai

Keyword(s):

Molecular Dynamics ◽

Low Temperatures ◽

Rotational Frequency ◽

The Other ◽

Present System ◽

Eccentric Rotation ◽

Axial Oscillation ◽

Axial Translation ◽

Dynamics Simulations ◽

Thermal Vibrations

It was discovered that large-amplitude axial oscillation can occur on a rotor with an internally hydrogenated deformable part (HDP) in a rotation–translation nanoconverter. The dynamic outputs of the system were investigated using molecular dynamics simulations. When an input rotational frequency (100 GHz > ω > 20 GHz) was applied at one end of the rotor, the HDP deformed under the centrifugal and van der Waals forces, which simultaneously led to the axial translation of the other end of the rotor. Except at too high an input rotational frequency (e.g., >100 GHz), which led to eccentric rotation and even collapse of the system, the present system could generate a periodic axial oscillation with an amplitude above 0.5 nm at a temperature below 50 K. In other ranges of temperature and amplitude, the oscillation dampened quickly due to the drastic thermal vibrations of the atoms. Furthermore, the effects of the hydrogenation scheme and the length of HDP on the equilibrium position, amplitude, and frequency of oscillation were investigated. The conclusions can be applied to the design of an ideal nano-oscillator based on the present rotation–translation converter model.

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Molecular dynamics simulations of the O2− ion mobility in dense Ne gas at low temperature: Influence of the repulsive part of the ion-neutral interaction potential

IEEE Transactions on Dielectrics and Electrical Insulation ◽

10.1109/tdei.2018.007080 ◽

2018 ◽

Vol 25 (5) ◽

pp. 1992-1998 ◽

Cited By ~ 1

Author(s):

A. F. Borghesani ◽

F. Aitken

Keyword(s):

Molecular Dynamics ◽

Low Temperature ◽

Molecular Dynamics Simulations ◽

Interaction Potential ◽

Ion Mobility ◽

Temperature Influence ◽

Dynamics Simulations ◽

Repulsive Part

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Size Effect in the Shear-Coupled Migration of Grain Boundaries Pinned by Triple Junctions

MRS Proceedings ◽

10.1557/proc-1224-gg07-03 ◽

2009 ◽

Vol 1224 ◽

Author(s):

Javier Gil Sevillano ◽

Aitor Luque ◽

Javier Aldazabal ◽

José Manuel Martinez-Esnaola

Keyword(s):

Molecular Dynamics ◽

Simple Model ◽

Low Temperature ◽

Size Effect ◽

Model Structure ◽

Triple Junctions ◽

Columnar Grains ◽

Tilt Boundaries ◽

Relationship Breakdown ◽

Dynamics Simulations

AbstractThis paper presents molecular dynamics simulations of shear-coupled migration of tilt boundaries pinned by triple junctions in a simple model structure of columnar grains of different sizes. Simulations are for copper at 300 K. The phenomenon is of interest as a possible explanation of the Hall-Petch relationship breakdown in nano-grained polycrystals deformed at high or moderate strain rate and low-temperature.

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Mechanisms of Molecular Beam Epitaxial Growth on Reconstructed Si{100}: Thermal and Energized Beams

MRS Proceedings ◽

10.1557/proc-141-419 ◽

1988 ◽

Vol 141 ◽

Cited By ~ 2

Author(s):

B. J. Garrison ◽

M. T. Miller ◽

D.W. Brenner

Keyword(s):

Molecular Dynamics ◽

Low Temperature ◽

Epitaxial Growth ◽

Gas Phase ◽

Molecular Beam ◽

Energy Deposition ◽

Amorphous Structure ◽

Molecular Beam Epitaxial ◽

Dynamics Simulations ◽

Molecular Beam Epitaxial Growth

Summary:Molecular dynamics simulations have been performed that examine the microscopic mechanisms of rearrangements of atoms on the Si{ 1001 surface due to deposition of gas phase atoms. For thermal energy deposition we find that the gas atoms initially attach to dangling bonds of the surface dimer atoms. The dimer ’unreconstruction’ is due to a diffusion event on the surface, thus is temperature activated. We also find that dimers may open in regions of the surface where there are several atoms not at lattice sites, thus a low temperature amorphous structure. For 5-10 eV deposition there are direct mechanisms of dimer opening that occur on the 50-100 fs timescale. For energies greater than 15-20 eV there is implantation of the silicon atoms which leads to subsurface damage.

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Quantum Molecular Dynamics Simulations of Low-Temperature High Energy Density Matter: Solid p-H2/Li and p-H2/B

The Journal of Physical Chemistry A ◽

10.1021/jp992098d ◽

1999 ◽

Vol 103 (47) ◽

pp. 9512-9520 ◽

Cited By ~ 12

Author(s):

Soonmin Jang ◽

Seogjoo Jang ◽

Gregory A. Voth

Keyword(s):

Molecular Dynamics ◽

Energy Density ◽

Low Temperature ◽

Molecular Dynamics Simulations ◽

High Energy ◽

High Energy Density ◽

Quantum Molecular Dynamics ◽

Dynamics Simulations ◽

Density Matter

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Stability of an Axial Thrust Self-Balancing System

Journal of Fluids Engineering ◽

10.1115/1.4023197 ◽

2013 ◽

Vol 135 (1) ◽

Cited By ~ 5

Author(s):

Takashi Shimura ◽

Satoshi Kawasaki ◽

Masaharu Uchiumi ◽

Toshiya Kimura ◽

Mitsuaki Hayashi ◽

...

Keyword(s):

Large Amplitude ◽

High Speed ◽

System Analysis ◽

Axial Direction ◽

Radial Pressure ◽

Liquid Hydrogen ◽

Axial Vibration ◽

Axial Thrust ◽

Balance System ◽

Excited Vibration

Rocket pumps are characterized by high speed and high delivery pressure. Therefore, balancing of axial thrust acting on the rotor assembly is one of the most important factors. To realize complete axial thrust balancing, a balance piston-type axial-thrust self-balancing system is often used in rocket pumps. This axial thrust balance system acts dynamically as if it were a mass and spring system, although there is no mechanical spring. Sometimes, large amplitude axial vibration is observed in a liquid hydrogen turbopump. Too much vibration in the axial direction causes metal-to-metal rubbing, resulting in fatal accidents of rocket turbopumps. However, the cause of the vibration has not yet been clarified. In the present study, the self-balancing system was modeled by combining the mechanical structure and the fluid system in a calculation program of one-dimensional multidomain system analysis software. Stability of the system was investigated using this program and the possibility of existence of self-excited vibration was confirmed. Effects of geometry, fluids, viscous damping, radial pressure drop in the chamber, and orifice flow coefficients on the stability of the balance piston system were examined. As a result, it was concluded that large compressibility of liquid hydrogen was the cause of the large amplitude axial vibrations. With the results of analyses, methods to stabilize the system in order to suppress the axial vibration were suggested.

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