Structural Changes of Circularly Defected Monolayer Circular Graphene Nanosheets Upon Mechanical Vibrations

2021 ◽  
Author(s):  
M. Farzannasab ◽  
M. M. Khatibi ◽  
S. Sadeghzadeh
Keyword(s):  
Natural Frequency ◽  
Structural Changes ◽  
Graphene Nanosheets ◽  
Frequency Domain Analysis ◽  
Graphene Sheets ◽  
Interior Boundary ◽  
Circular Holes ◽  
Circular Defect ◽  
Hole Boundary ◽  
Interior Boundary Conditions

As the strongest and toughest material known, graphene has found numerous applications in various types of sensors. Due to the great influences of the graphene sheet’s geometry on resonance frequency, circular defects could effect on expected results of sensors. Circular holes in circular graphene sheets (CGSs) have been modeled with molecular dynamics (MD) simulation in the present work. Then the vibration behavior of intact circular plate and circular sheet with the circular defect has been investigated using frequency-domain analysis (FDD). Furthermore, for validating the used method, the obtained natural frequencies for different graphene sheets have been compared with acquired data in former research. The result of validation showed the accuracy of the used method in this study. The results indicated that by increasing the hole size, the natural frequency of a defected sheet with free edges will be diminished, and with simply-supported interior boundary conditions typically went up. Also, by increasing the hole’s eccentricity, the natural frequency of the defected graphene sheet will be diminished when the hole boundary was subjected to simply-support or free condition.

scholarly journals A Vibration-Based Structural Health Monitoring System for Transmission Line Towers

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 515 ◽  
Author(s):  
Long Zhao ◽  
Xinbo Huang ◽  
Ye Zhang ◽  
Yi Tian ◽  
Yu Zhao
Keyword(s):  
Structural Health Monitoring ◽  
Transmission Line ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Transmission Tower ◽  
Health Monitoring System ◽  
Wind Speeds ◽  
Before And After

In this paper, we present a vibration-based transmission tower structural health monitoring system consisting of two parts that identifies structural changes in towers. An accelerometer group realizes vibration response acquisition at different positions and reduces the risk of data loss by data compression technology. A solar cell provides the power supply. An analyser receives the data from the acceleration sensor group and calculates the transmission tower natural frequencies, and the change in the structure is determined based on natural frequencies. Then, the data are sent to the monitoring center. Furthermore, analysis of the vibration signal and the calculation method of natural frequencies are proposed. The response and natural frequencies of vibration at different wind speeds are analysed by time-domain signal, power spectral density (PSD), root mean square (RMS) and short-time Fouier transform (STFT). The natural frequency identification of the overall structure by the stochastic subspace identification (SSI) method reveals that the number of natural frequencies that can be calculated at different wind speeds is different, but the 2nd, 3rd and 4th natural frequencies can be excited. Finally, the system was tested on a 110 kV experimental transmission line. After 18 h of experimentation, the natural frequency of the overall structure of the transmission tower was determined before and after the tower leg was lifted. The results show that before and after the tower leg is lifted, the natural frequencies of each order exhibit obvious changes, and the differences in the average values can be used as the basis for judging the structural changes of the tower.

scholarly journals Multishelled NiO Hollow Spheres Decorated by Graphene Nanosheets as Anodes for Lithium-Ion Batteries with Improved Reversible Capacity and Cycling Stability

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Lihua Chu ◽  
Meicheng Li ◽  
Yu Wang ◽  
Xiaodan Li ◽  
Zipei Wan ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Graphene Nanosheets ◽  
Hollow Spheres ◽  
Modern Science ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Graphene Sheets ◽  
Reduced Graphene ◽  
Graphene Nanocomposite ◽  
A Current

Graphene-based nanocomposites attract many attentions because of holding promise for many applications. In this work, multishelled NiO hollow spheres decorated by graphene nanosheets nanocomposite are successfully fabricated. The multishelled NiO microspheres are uniformly distributed on the surface of graphene, which is helpful for preventing aggregation of as-reduced graphene sheets. Furthermore, the NiO/graphene nanocomposite shows much higher electrochemical performance with a reversible capacity of 261.5 mAh g−1at a current density of 200 mA g−1after 100 cycles tripled compared with that of pristine multishelled NiO hollow spheres, implying the potential application in modern science and technology.

Preparation and Characterization of In Situ Nanocomposites of Graphene Nanosheets/Polyurethane

2019 ◽  
Vol 814 ◽  
pp. 90-95 ◽  
Author(s):  
Guang Lei Lv ◽  
Yuan Yuan Li ◽  
Chen Fei ◽  
Zhi Hao Shan ◽  
Jing Gan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Tensile Strength ◽  
Graphene Nanosheets ◽  
Graphene Sheets ◽  
Microstructural Properties ◽  
Wear Performance ◽  
Polyurethane Composites

Graphene nanosheets/polyurethane (GNS/PU) was prepared in situ by polymerization technique for the manufacture of PU safety shoes soles. The graphene nanosheets/polyurethane composites were characterized for their mechanical properties, thermal conductivity and abrasion resistance, and comparison is made with those of the neat polyurethane. The microstructural properties of GNS/PU were characterized by SEM. The results show that with the increase of the amount of graphene within the range of weight-percentages analyzed, the tensile strength of the composites gradually increases. The tensile strength of the GNS/PU composites increased to 64.14 MPa with 2 wt% GNS, compared with 55.1 MPa for neat PU. When the graphene sheets reached 2 wt%, the abrasion volume reached 71 mm3. Compared with the pure PU, the wear performance of GNS/PU composites was significantly improved.

scholarly journals Multi-time formulation of particle creation and annihilation via interior-boundary conditions

2019 ◽  
Vol 32 (02) ◽  
pp. 2050004 ◽  
Author(s):  
Matthias Lienert ◽  
Lukas Nickel
Keyword(s):  
Boundary Conditions ◽  
Fock Space ◽  
Lorentz Invariance ◽  
Particle Creation ◽  
Wave Functions ◽  
Constant Matrix ◽  
Relativistic Case ◽  
Interior Boundary ◽  
Particle Creation And Annihilation ◽  
Interior Boundary Conditions

Interior-boundary conditions (IBCs) have been suggested as a possibility to circumvent the problem of ultraviolet divergences in quantum field theories. In the IBC approach, particle creation and annihilation is described with the help of linear conditions that relate the wave functions of two sectors of Fock space: [Formula: see text] at an interior point [Formula: see text] and [Formula: see text] at a boundary point [Formula: see text], typically a collision configuration. Here, we extend IBCs to the relativistic case. To do this, we make use of Dirac’s concept of multi-time wave functions, i.e. wave functions [Formula: see text] depending on [Formula: see text] space-time coordinates [Formula: see text] for [Formula: see text] particles. This provides the manifestly covariant particle-position representation that is required in the IBC approach. In order to obtain rigorous results, we construct a model for Dirac particles in 1+1 dimensions that can create or annihilate each other when they meet. Our main results are an existence and uniqueness theorem for that model, and the identification of a class of IBCs ensuring local probability conservation on all Cauchy surfaces. Furthermore, we explain how these IBCs relate to the usual formulation with creation and annihilation operators. The Lorentz invariance is discussed and it is found that, apart from a constant matrix (which is required to transform in a certain way), the model is manifestly Lorentz invariant. This makes it clear that the IBC approach can be made compatible with relativity.

Synthesis of FeC2O4-Graphene Composites and their Application in Removal Dyes

2012 ◽  
Vol 463-464 ◽  
pp. 533-537 ◽  
Author(s):  
Shui Sheng Wu ◽  
Ya Ming Wang ◽  
Qing Ming Jia ◽  
Li Li Gu ◽  
Yan Lin Sun
Keyword(s):  
Energy Storage ◽  
Graphene Nanosheets ◽  
Chemical Precipitation ◽  
Chemical Precipitation Method ◽  
Precipitation Method ◽  
Energy Storage Materials ◽  
Graphene Sheets ◽  
Storage Materials ◽  
Simple Chemical

A well-organized composite of graphene nanosheets decorated with FeC2O4 particles was synthesized through a simple chemical precipitation method. The FeC2O4 nanoparticles obtained were 100-150 nm in size and homogeneously anchored on graphene sheets as spacers to keep the neighboring sheets separated. The FeC2O4-graphene exhbited excellent performances in absorption propties and supercapacitor make potential uses as environment and energy storage materials in future.

Frequency domain analysis of modes in a photonic crystal micro-opto-electro-mechanical system with periodically arranged circular holes

2012 ◽  
Vol 44 (3-5) ◽  
pp. 273-277
Author(s):  
Ugur Akcakoca ◽  
Bernd Witzigmann ◽  
Ricardo Zamora ◽  
Thomas Kusserow ◽  
Hartmut Hillmer
Keyword(s):  
Photonic Crystal ◽  
Mechanical System ◽  
Frequency Domain ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Circular Holes

Yolk Type Asymmetric Ag–Cu2O Hybrid Nanoparticles on Graphene Substrate as Efficient Electrode Material for Hybrid Supercapacitors

2018 ◽  
Vol 233 (1) ◽  
pp. 85-104 ◽  
Author(s):  
Mukesh Kumar ◽  
Himani Chauhan ◽  
Biswarup Satpati ◽  
Sasanka Deka
Keyword(s):  
Electrode Material ◽  
Electrochemical Impedance ◽  
Graphene Nanosheets ◽  
High Energy ◽  
Hybrid Nanostructures ◽  
High Energy Density ◽  
Hybrid Nanoparticles ◽  
Graphene Sheets ◽  
Hybrid Supercapacitors ◽  
Metal Metal

Abstract Yolk type asymmetric Ag–Cu2O hybrid nanostructures are in situ synthesized on reduced graphene oxide (RGO) sheets for the first time under one pot hydrothermal mild reaction condition. The co-reduction method provides a facile and straight forward approach to metal/metal oxide hybrid NPs growth on graphene nanosheets and the nano heterostructures are found to be homogeneously distributed over graphene sheets with unique yolk type morphology forming Ag–Cu2O/RGO nanocomposite (NC). The supercapacitor performances of the NCs are evaluated in aqueous 6.0 M KOH by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) in two electrode cell assembly using Ag-Cu2O/RGO as electrode material. The ternary NCs exhibit excellent hybrid capacitance behavior having ~812 Fg−1 specific capacitance value with high energy density 27.2 Wh kg−1 and power density 285 W kg−1, respectively, at current density of 0.5 Ag−1 that suits for potential applications in hybrid capacitor. The high capacitance property of ternary NCs without use of binder can be attributed to excellent electronic/ionic conductivity due to presence of highly conductive graphene sheets in addition of noble Ag metal and unique yolk type morphology which causes faster electronic conduction among different components of the electrode material.

scholarly journals Response of fusion plasma-facing materials to nanosecond pulses of extreme ultraviolet radiation

2018 ◽  
Vol 36 (3) ◽  
pp. 293-307 ◽  
Author(s):  
Jaroslav Straus ◽  
Karel Kolacek ◽  
Jiri Schmidt ◽  
Oleksandr Frolov ◽  
Monika Vilemova ◽  
...  
Keyword(s):  
Structural Changes ◽  
Focused Ion Beam ◽  
Extreme Ultraviolet ◽  
Laser Energy ◽  
Ion Beam ◽  
Fusion Plasma ◽  
Nanosecond Pulses ◽  
Circular Holes ◽  
Crater Morphology ◽  
Extreme Ultraviolet Radiation

AbstractThe experimental study of damage to tungsten (W), molybdenum (Mo), and silicon carbide (SiC) surfaces induced by focused extreme ultraviolet laser radiation (λ ~ 47 nm/~1.5 ns/21–40 µJ) is presented. It was found that W and Mo behaved similarly: during the first shot, the damaged area is covered by melted and re-solidified material, in which circular holes appear – residua of just opened pores/bubbles, from which pressurized gas/vapors escaped. Next cracks and ruptures appear and the W has a tendency to delaminate its surface layer. Contrary, single-crystalline SiC has negligible porosity and sublimates; therefore, no escape of “pressurized” gas and no accompanying effects take place. Moreover, SiC at sublimating temperature decomposes to elements; therefore, the smooth crater morphology can be related to local laser energy density above ablation threshold. When more shots are accumulated, in all three investigated materials, the crater depth increases non-linearly with number of these shots. The surface morphology was investigated by an atomic force microscope, the surface structure was imaged by a scanning electron microscope (SEM), and the structure below the surface was visualized by SEM directed into a trench that is milled by focused ion beam. Additionally, structural changes in SiC were revealed by Raman spectroscopy.

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