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Plasmonic responses of Cua??Ag bimetallic system: Influence of distinctiveness and arrangements
摘要： In this article, the effect of the distinctiveness and arrangements on the plasmonic resonance of Cu–Ag system were studied by finite element method, and the effect of morphologies on the plasmonic properties of Cu@Ag core@shell NPs and Cu–Ag corn-cob liked NPs was investigated by experiment. For Cu@Ag core-shell structure, as the fixed thickness of Ag-shell at 10 nm, the dipole plasmon resonance gradually blue-shifts with increasing the radius of Cu core, and as the fixed radius of Cu-core at 50 nm, the feature peak shows a red-shift and broadening with increasing the thickness of Ag shell. For Cu–Ag corn-cob structure, the feature for different Ag coverage are similar to each other and most of the them follow the blue-shifted tendency with the increase the degree of Ag-coverage. Furthermore, as the regular-shaped structure increases (form trigonal to spherical), the plasmon resonance gradually blue shifts, and finally, we use two parameters to describe the different idealized Cu–Ag structure: separation, exterior contact, intersection and core@shell. The combined information from our simulation and experiment will give guidelines for choosing adequate particles when aiming at certain plasmonic properties.
关键词： Finite element method,Structure-property,Core-shell,Cu–Ag corn-cob-liked,Plasmonic absorption
更新于2025-09-23 15:19:57
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Tandem laser-gas metal arc welding joining of 20a??mm thick super duplex stainless steel: An experimental and numerical study
摘要： The present work covers the topic of strains and stresses prediction in case of welded steel structures. Steel sheets of 20 mm thickness made in URTM2507Cu are welded using a laser and gas metal arc welding processes combination. The focused laser beam leads the arc in a Y-shape chamfer geometry. Both sources are 20 mm apart from each other in order to avoid any synergic effect with each other. In order to predict residual strain, a 3D unsteady numerical simulation has been developed in COMSOL finite element software. A volume heat source has been identified based on the temperature measurements made by 10 K-type thermocouples, implanted inside the workpiece. The 50 mm deep holes are drilled in the workpiece using dye-sinking Electrical Discharge Machining (EDM) machine. Before the implantation in the hole, each thermocouple is surrounded by Inconel sheathing. Hot junctions of the thermocouples are positioned in a way to feel two advancing molten pools. The equivalent heat source is composed of three sources. First one is a Goldak source that represents the molten pool induced by gas metal arc welding. The second one is a cylinder with an elliptic cross-section that represents the focused laser beam penetrating into the workpiece. The third one is a surface Gaussian source that represents energy radiated by arc and blocked by workpiece surface. Concerning mechanical simulation, an elasto-plastic behavior with isotropic hardening is implemented. A weak coupling is established between equations governing heat transfer and mechanics thanks to the temperature dependent coefficient of linear expansion. This numerical simulation made with some simplifying assumptions predicts an angular distortion and a longitudinal shrinkage of the welded structure. The numerical results are consistent with the displacements measured by digital image correlation method.
关键词： welding,simulation,Finite element method,materials processing,laser-gas metal arc welding,thermomechanics
更新于2025-09-23 15:19:57
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Multiple Fano resonances in MIM waveguide with umbrella resonator coupled with metal baffle for refractive index sensing
摘要： A single baffle metal-insulator-metal (MIM) waveguide coupled with a semi-circular cavity and a cross-shaped cavity is proposed based on the multiple Fano resonances characteristics of Surface Plasmonic Polaritons (SPPs) subwavelength structure. The isolated state formed by two resonators interferes with the wider continuous state mode formed by the metal baffle, forming Fano resonance independently could tune to five different modes. The formation mechanism of Fano resonance is analyzed based on the multimode interference coupled mode theory (MICMT). Finite element method (FEM) and MICMT are used to simulate the transmission spectra of this structure and analyze the influence of structural parameters on the refractive index sensing characteristics. And the transmission responses calculated by FEM simulation are consistent with the MICMT theoretical results very well. The results show that the Figure of Merit(FOM) can reach 193 and the ultra-high sensitivity is 1600nm/RIU after optimizing the structure parameters, which can provide theoretical basis for the design of high sensitive refractive index sensors based on SPPs waveguide for high-density photonic integration with excellent performance in the near future.
关键词： The MIM waveguide,Surface Plasmonic Polaritons,Finite element method,Fano resonance
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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Modelling the propagation of electromagnetic waves across complex metamaterials in closed structures
摘要： Metamaterials are currently one of the most popular fields in microwave technology because their particular electromagnetic properties lead to a plenty of very relevant applications, both military and civilian. Additionally, the analysis and design of microwave components based on this kind of materials is one of the more challenging problems found by the applied electromagnetism community due to the complexity introduced in the mathematical formulation by their constitutive relationships. The most general case of metamaterial is the bi-anisotropic one, where both the electric field and the electric induction simultaneously depend on the magnetic field and the magnetic induction. In this paper, we present a new and powerful Finite Element Method scheme valid for the analysis of the most general waveguides, filled with lossy bi-anisotropic linear materials. Edge elements have been used in order to prevent the appearance of spurious solutions and the final eigensystems are very sparse, thus allowing a great memory and computing time saving.
关键词： Bi-anisotropic metamaterials,Microwave engineering,Weighted residuals method,Finite Element Method
更新于2025-09-19 17:15:36
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Polarized radiative transfer in complex media exposed to external irradiation
摘要： Polarized radiative transfer problems in two-dimensional complex media exposed to external irradiation are numerically investigated. The numerical algorithm used is a discontinuous finite element method (DFEM) where unstructured triangular meshes are applied to discretize the computational domain with irregular geometries. In the DFEM application, the discrete elements are assumed to be separated from each other, the shape functions are locally constructed on each element, and the computation domain is connected by simulating the numerical flux across the inner-element boundaries using the up-winding scheme. Thus the DFEM can eliminate the computation errors in the conventional finite element method (FEM) where the inner-elements are forced to be continuous. In this paper, the derivation of the DFEM discretization for vector radiative transfer equation (VRTE) is presented, the correctness of the DFEM for VRTE is validated, and polarized radiative transfer problems in several irregular media are carried out. The distributions of Stokes vector components and radiative flux are presented and analyzed.
关键词： Complex geometry,Stokes vector component,Participating medium,Polarized radiative transfer,Discontinuous finite element method
更新于2025-09-19 17:15:36
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Broadband Dispersion Compensation of Single Mode Fiber by using Modified Decagonal Photonic Crystal Fiber having High Birefringence
摘要： This paper presents a highly birefringent dispersion compensating microstructure modified decagonal photonic crystal fiber for broadband transmission communication system. According to simulation, negative dispersion coefficient of ?610 ps/(nm.km) and a relative dispersion slope (RDS) close to that of single mode fiber of about 0.0036 nm-1 with birefringence of the order 2.1×10-2 was obtained at 1550 nm. The variation of structural parameters is also studied to evaluate the tolerance of the fabrication. Moreover, effective area, residual dispersion, effective dispersion, confinement loss, and nonlinear coefficient of the proposed modified decagonal photonic crystal fiber (M-DPCF) are also mentioned and discussed.
关键词： Photonic crystal fiber,Birefringence,Dispersion compensating fiber,Effective mode area,Residual dispersion,Full-vector Finite Element Method
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
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Vibration analysis and control of fluid containers using piezoelectrically-excited side wall
摘要： The vibration analysis and control of containers with heavy loaded fluid is undertaken in this paper. The problem of fluid–structure vibration is viewed and analyzed from several viewpoints including both analytical methods and numerical techniques. In order to effectively control the fluid–structure vibration, one of the side walls is made flexible where two piezoelectric patches are utilized to sense the distributed displacements resulting from fluid-structure movements, while the other one is used to actively control the vibration. For this, a boundary control technique is used to actively control the multi-modal vibration of fluid–structure. The simulation results for the analytical models are further validated using a comprehensive finite element method. Before applying the proposed controller, the results show that the fluid vibration is different in different heights and distances. However, the simulation results indicate that the piezoelectrically-excited beam is able to suppress the vibrations of all the positions very effectively and quickly. These results prove the feasibility of utilizing piezoelectrically-excited beams in vibration control of fluid–structure.
关键词： boundary control,piezoelectric-based vibration control,finite element method,Fluid–structure interaction
更新于2025-09-19 17:15:36