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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field emission from vertically-aligned graphene edges on graphitized pencil lead
摘要： We have already demonstrated that the graphitized mechanical pencil lead show superior field emission features in high emission current regime [1]. In this paper, we present the results of additional detailed analysis of field emission from completely graphitized pencil lead including Raman scattering, FIM/FEM images and energy distributions of emitted electrons as well as field emission characteristics also in low emission current regime. It is concluded again that the fully graphitized pencil lead is promising as low cost but superior field emitters
关键词： graphite,energy distribution,FIM,FEM,vertically-aligned graphene,field emission
更新于2025-09-23 15:21:21
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Laser fabrication of structural bone: surface morphology and biomineralization assessment
摘要： The current work explores the surface morphology of the laser-ablated bone using Yb-fiber coupled Nd:YAG laser (λ = 1064 nm) in continuous wave mode. As the laser-ablated region contains physiochemically modified carbonized and nonstructural region, it becomes unknown material for the body. Thus, biomineralization on such a laser-ablated region was assessed by in vitro immersion test in noncellular simulated body fluid. The presence of hydroxyapatite was detected in the precipitated mineral product using scanning electron microscopy equipped with energy dispersive spectroscopy, and X-ray diffraction analysis. The effect of varying laser parameters on distribution of surface morphology features was identified and its corresponding effect on biomineralization was studied.
关键词： Laser-bone interaction,Surface morphology,Finite element method (FEM) modeling,Laser ablation
更新于2025-09-23 15:21:01
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Taguchi Grey Relationalapproach Foroptimizing Process Parameters of Laser Peeningontitanium Alloy to Induce Enhanced Compressive Stress Based on Finite Element Simulation
摘要： Laser Shock Peening (LSP) turned out the most efficient surface engineering process for advanced materials to induce beneficial deep compressive residual stress which helps in improving mechanical, fatigue properties and surface damage resistance. But, analyzing the non-uniform distribution of residual stresses in the treated sample with XRD is much time taking and costly process. This problem can be resolved with LSP finite element numerical simulation model which is feasible with the realistic experimental process. The FE model allows the user to control the laser parameters in order to achieve the optimal level of all controllable parameters. The present study is intended to analyze and optimize the influence of laser processing parameters assists in inducing the residual compressive stress with minimal surface deformation.A Ti6Al4V material model with Johnson-Cook’s visco-elastic-plastic material behaviour law is prepared for LSP simulation. And Gaussian pressure profile is utilized for uniform loading of the targeted zone for the proposed model. Taguchi Grey Relational Analysis (TGRA) with L27 orthogonal array is applied to LSP simulation, and the results were analyzed with consideration of multiple response measures. It is noted that surface deformation is increased with the rise in a number of laser shots and pressure pulse duration. Maximum compressive residual stresses are falling for higher levels of laser spot diameter, Laser spot overlap and Laser Power density. The correlation is observed between FE simulation and published results. The optimal set of process parameters are obtained for improving the LSP on Ti alloys.
关键词： Grey Relational Analysis (GRA),Taguchi Technique,Laser Shock Peening (LSP),Finite Element Method (FEM),Residual Stresses
更新于2025-09-23 15:21:01
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Nuclear Power Plant Prestressed Concrete Containment Vessel Structure Monitoring during Integrated Leakage Rate Testing Using Fiber Bragg Grating Sensors
摘要： As the last barrier of nuclear reactor, prestressed concrete containment vessels (PCCVs) play an important role in nuclear power plants (NPPs). To test the mechanical property of PCCV during the integrated leakage rate testing (ILRT), a fiber Bragg grating (FBG) sensor was used to monitor concrete strain. In addition, a finite element method (FEM) model was built to simulate the progress of the ILRT. The results showed that the strain monitored by FBG had the same trend compared to the inner pressure variation. The calculation results showed a similar trend compared with the monitoring results and provided much information about the locations in which the strain sensors should be installed. Therefore, it is confirmed that FBG sensors and FEM simulation are very useful in PCCV structure monitoring.
关键词： structure health monitoring (SHM),finite element method (FEM),integrated leakage rate test (ILRT),fiber Bragg grating (FBG),prestressed concrete containment vessel (PCCV)
更新于2025-09-23 15:21:01
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Investigation into effect of coupled resonance phenomenon towards sensitivity enhancement of SAW conductivity sensors integrated with ZnO nanorods
摘要： In this work, FEM simulation was used to investigate the sensitivity of a one-port surface acoustic wave (SAW) resonator sensor to changes in electrical conductivity of the sensing medium composed of ZnO nanorods offering elastic loading on the surface of the resonator. A system of coupled resonators was formed when the height of the ZnO nanorods attached to the surface of the resonator was adjusted such that the resonant frequency of the nanorod approached the original resonant frequency of the SAW resonator. It was observed that the use of ZnO nanorods of resonant dimensions as sensing medium could enhance the sensitivity of the composite SAW sensor to changes in electrical conductivity of the sensing medium by up to 79 times. The comparatively higher sensitivity of the SAW conductivity sensor utilizing ZnO nanorods at resonant dimensions as sensing medium was attributed to the fact that the system of coupled resonators thus formed operates at a state of high sensitivity to changes induced in piezoelectric stiffening of the substrate during SAW propagation. The observations from FEM simulation conducted in the present work suggests strong prospects for the use of coupled resonance phenomenon at nanoscale for enhancing the sensitivity of conductivity-based SAW gas sensors and UV detectors employing 1-D ZnO nanostructures as sensing medium.
关键词： ZnO nanorods,sensitivity enhancement,SAW resonator,coupled resonance,FEM simulation
更新于2025-09-23 15:19:57
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[IEEE 2020 IEEE Texas Power and Energy Conference (TPEC) - College Station, TX, USA (2020.2.6-2020.2.7)] 2020 IEEE Texas Power and Energy Conference (TPEC) - Semi-Seasonally Optimized Tilt Angles for Design of Utility-Scale Photovoltaic Generation Station
摘要： In this paper, a solution to the double curl equation with generalized Coulomb gauge is proposed based on the vectorial representation of the magnetic vector potential. Traditional Coulomb gauge is applied to remove the null space of the curl operator and hence the uniqueness of the solution is guaranteed. However, as the divergence operator cannot act on edge elements (curl-conforming) directly, the magnetic vector potential is represented by nodal elements, which is too restrictive, since both the tangential continuity and the normal continuity are required. Inspired by the mapping of Whitney forms by mathematical operators and Hodge (star) operators, the divergence of the magnetic vector potential, as a whole, can be approximated by Whitney elements. Hence, the magnetic vector potential can be expanded by the edge elements, where its vectorial nature is retained and only the tangential continuity is required. Finally, the original equation can be rewritten in a generalized form and solved in a more natural and accurate way using finite-element method.
关键词： Whitney forms,generalized Coulomb gauge,Finite-element method (FEM),magnetostatic
更新于2025-09-23 15:19:57
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Hierarchically decomposed finite element method for a triply coupled piezoelectric, structure, and fluid fields of a thin piezoelectric bimorph in fluid
摘要： This paper proposes a numerical method for analyzing a thin piezoelectric bimorph in fluid. A hierarchically decomposed finite element method (FEM) is proposed for modeling the triply coupled piezoelectric-structure–fluid interaction. The electromechanical coupling (piezoelectric-structure interaction) behavior in a thin piezoelectric bimorph is described by the classical constitutive equation, the incompressible fluid flows by the Navier–Stokes equation and the structure by the Cauchy equation of motion. The piezoelectric-structure–fluid interaction system is decomposed into subsystems of fluid–structure interaction (FSI) and piezoelectric field, then the piezoelectric field and the FSI are coupled using the block Gauss–Seidel method, the fluid–structure interaction is split into the fluid–structure velocity field and the pressure field using an algebraic splitting and the fluid–structure velocity field is partitioned into fluid velocity field and structure velocity field. Using the proposed method, the resonance characteristics of a piezoelectric bimorph cantilever made of PVDF and PZT-5H material in fluid are investigated for actuation and sensor configurations.
关键词： Thin piezoelectric bimorph,Hierarchical decomposition,Finite element method (FEM),Fluid–structure interaction (FSI),Piezoelectricity,Piezoelectric-structure interaction
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Finite Element Modelling and Computational Analysis of Mechanical Properties of Carbon Composite-Based Love Wave Sensor
摘要： Structured materials are of interest to emphasize the sensitivity of gas or bio-sensors. This work focuses on carbon-polymer composite (PEDOT:PSS-MWCNT) and additional multiwalled carbon nanotubes (MWCNT), deposited by inkjet printing on Love acoustic wave devices. This combination is studied, both with simulation based on finite element modelling and computational analysis of a reduced model, and experimental measurements. This allows for an estimation of the Young modulus of each material: 70 GPa and 150 GPa for the PEDOT:PSS-MWCNT bilayer composite material (? 450nm) and for the MWCNT bilayer on carbon composite (?140nm), respectively. The value is lower than that obtained in the literature, which has been attributed to the material porosity. An enhanced waveguiding effect is observed, which is interesting for further detection applications.
关键词： MWCNT,PEDOT:PSS,Gas sensor,FEM,SAW,Bio sensor
更新于2025-09-19 17:15:36
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Numerical-experimental study on polishing of silicon wafer using magnetic abrasive finishing process
摘要： Silicon wafer as a brittle material is extensively used in semiconductors. The surface quality of this material significantly affects the quality and efficiency of related components. In this study, the coupled algorithm of SPH/FEM is used to simulate the surface polishing of silicon wafers with Magnetic Abrasive Finishing process. The effects of rotational speed and machining gap on percent change in surface roughness (%?Ra) and material removal (MR) are comprehensively analyzed with simulations and experiments. Furthermore, the material removal mechanism in wafers was investigated by using AFM. Our observations showed that both micro-fracture and micro-cutting mechanisms might happen and it highly depends on polishing parameters. Results of the simulations and experimental data showed that MR and %?Ra value increase with increasing rotational speed and decreasing machining gap. According to our experimental findings, maximum %?Ra and MR are 65% and 39.09 mg, respectively.
关键词： Material removal,Surface Roughness,Magnetic Abrasive Finishing,Al2O3,FEM/SPH,Silicon Wafer,Nano-finishing
更新于2025-09-19 17:15:36
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Core-shell structure-induced high displacement response in piezoelectric ceramics: A theoretical design
摘要： In this work, a series of piezoelectric composites with core-shell structure are proposed to pursue high displacement response under a low applied electric field. The shell and core consist of piezoelectric and non-piezoelectric material, respectively. A finite element method (FEM) is introduced to simulate the distribution of local electric field and the displacement response. The results show that the largest piezoelectric displacement response of these core-shell structural composites reaches twenty-five times larger than that of pure piezoelectric ceramic under the applied electric field of 2 kV/mm, which can be explained by the fact that the local electric field inside the shell is enhanced up to dozens of times as large as the applied electric field. It is also suggested that the displacement response of piezoelectric composites can be heightened by adopting smaller shell volume fraction, or increasing the permittivity or decreasing the Young's modulus of the core.
关键词： Displacement response,Finite element method (FEM),Core-shell structure,Piezoelectric
更新于2025-09-19 17:15:36