Abstract For the purpose of improving the interface and mechanical properties of carbon fiber reinforced polymer (CFRP) composites, a new strategy was proposed to graft the graphene oxide (GO) onto carbon fiber (CF) surface fast and effectively via thiol‐ene click chemistry reaction using vinyl‐terminated hyperbranched polyester (VHBP) as bridging agent. The successful synthesis of the CF‐VHBP‐GO hybrid reinforcement was verified through Fourier transform infrared spectroscopy (FT‐IR), x‐ray photoelectron spectroscope, thermogravimetric analysis, and scanning electron microscopy. The simultaneous introduction of GO and hyperbranched polymers changed the fiber surface morphology and improved the wettability and surface energy of CF. Judging from the results of the micro‐droplet test, the interfacial shear strength for epoxy (EP) based composite reinforced with CF‐VHBP‐GO was significantly increased by 137.8% compared to untreated CF/EP composite owing to the synergistic effect of VHBP and GO. In addition, the tensile and flexural strength for CF‐VHBP‐GO/EP composite were improved by 47.6% and 65.8%, respectively, compared to untreated CF/EP composite, respectively. This work offers a promising technique for developing high‐performance CF composites with excellent interface properties.
Ultra-wide spectrum light source plays an important role in large capacity fiber optic communication and fiber optic sensing. This paper designed an Er/Bi co-doped fiber, using a single-layer pumping structure on the performance of the designed fiber, which focuses on the pump power, fiber length on the performance of the output spectrum of Er/Bi codoped fiber. The experiment shows that doping formula of Erbium and Bismuth ions is beneficial to improve the intensity of L band emission line, which provides a basis for further revealing the intrinsic mechanism of Bismuth ions near infrared luminescence center. Finally, a high brightness ultra-wide spectrum light source of S+C+L band from 1450nm to 1700nm is obtained from the study of multi-parameter equalization method, in which 5dB bandwidth reached 105nm in the center of 1550nm wavelength, and the fluorescence intensity showed an upward trend after 1650nm wavelength. It can be seen that this light source will have a promising application prospect in the fields of large capacity optical fiber communication system and large capacity optical fiber sensing system.
Abstract The influences of Er content on the interfacial microstructure shear properties and creep properties of Sn58Bi joints were investigated in this study. The intermetallic compound composition of Sn58Bi-xEr/Cu was Cu6Sn5 compound. The addition of Er suppressed the activity of Sn element, decreased the driving force for the growth of Cu6Sn5 intermetallic compound and decreased the thickness of Cu6Sn5 intermetallic compound layer. The shear properties and creep durability of Sn58Bi-xEr/Cu welded joints were improved to a certain extent. At the Er content of 0.1%, the shear strength and creep durability properties of the solder alloy are relatively optimal. When wt%Er was more than 0.1%, with the increasing Er content of rare earth elements, the internal organization of the joint interface is coarsened, and the flatness of the IMC layer at the interface is reduced, which leads to the decrease of the creep performance of the final joint.
In this paper, a high sensitivity fiber temperature sensor based on surface plasmon resonance is designed and studied. In the simulation, the single mode fiber is polished to remove most of the cladding, and then gold and silver films are added. Finally, it is embedded in the heat shrinkable tube filled with a thermo-optic coefficient liquid for curing. The numerical simulation results show that the sensing characteristics are sensitive to the remaining cladding thickness of the fiber, the thickness of the gold film and the thickness of the silver film. When the thermo-optic coefficient of the filling liquid is -2.8 × 10
In order to investigate the effects of second-order hydrodynamic loads on a 15 MW floating offshore wind turbine (FOWT), this study employs a tool that integrates AQWA and OpenFAST to conduct fully coupled simulations of the FOWT subjected to wind and wave loadings. The load cases covering normal and extreme conditions are defined based on the met-ocean data observed at a specific site. The results indicate that the second-order wave excitations activate the surge mode of the platform. As a result, the surge motion is increased for each of the examined load case. In addition, the pitch, heave, and yaw motions are underestimated when neglecting the second-order hydrodynamics under the extreme condition. First-order wave excitation is the major contributor to the tower-base bending moments. The fatigue damage of the tower-base under the extreme condition is underestimated by 57.1% if the effect of second-order hydrodynamics is ignored. In addition, the accumulative fatigue damage over 25 years at the tower-base is overestimated by 16.92%. Therefore, it is suggested to consider the effects of second-order wave excitations of the floating platform for the design of the tower to reduce the cost of the FOWT.
Spatial variability is a natural attribute of soil properties and strongly affects seismic performance of earth structures. A novel stochastic dynamics method, probability density evolution method (PDEM), is proposed for seismic performance evaluation of retaining walls considering spatial variability of soil properties. Abundant probabilistic results of retaining wall, such as the mean, standard variance, evolution of probability density functions and dynamic reliability, are acquired in present study. It is found that neglecting the spatial variability of soil properties by treating soil properties as a uniform field in each realization may overrate the safety of the retaining wall.
Quantum effects in plasmonic systems play an important role in defining the optical response of structures with subnanometer gaps. Electron tunneling across the gaps can occur, altering both the far-field optical response and the near-field confinement and enhancement. In this study, we experimentally and theoretically investigate plasmon coupling in gold "nanomatryoshka" (NM) nanoparticles with different core–shell separations. Plasmon coupling effects between the core and the shell become significant when their separation decreases to 15 nm. When their separation decreases to below 1 nm, the near- and far-field properties can no longer be described by classical approaches but require the inclusion of quantum mechanical effects such as electron transport through the self-assembled monolayer of molecular junction. In addition, surface-enhanced Raman scattering measurements indicate strong electron-transport induced charge transfer across the molecular junction. Our quantum modeling provides an estimate for the AC conductances of molecules in the junction. The insights acquired from this work pave the way for the development of novel quantum plasmonic devices and substrates for surface-enhanced Raman scattering.
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