- 标题
- 摘要
- 关键词
- 实验方案
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Damage degree prediction method of CFRP structure based on fiber Bragg grating and epsilon-support vector regression
摘要： The assessment of structural damage is of great significance for ensuring the service safety of carbon fiber reinforced plastics (CFRP) structures. In this paper, the damage degree prediction method of CFRP structure based on fiber Bragg grating and epsilon-support vector regression was studied. The structural dynamic response signals were detected by fiber Bragg grating sensors. Then, the Fourier transform was used to extract the dynamic characteristics of the structure as the damage feature, and the damage feature dimensionality was reduced by using the RReliefF algorithm. On this basis, the damage degree prediction model of CFRP structure based on epsilon-support vector regression was established. Finally, the method proposed in this paper was experimentally verified. The results showed that the epsilon-support vector regression model can accurately predict the damage degree of unknown samples, and the absolute relative error of 27 experiments was less than 10% for 30 testing experiments. This paper provided a feasible method for predicting the damage degree of CFRP structures.
关键词： Frequency response,Carbon fiber reinforced plastics,Epsilon-support vector regression,RReliefF,Damage degree prediction
更新于2025-09-23 15:23:52
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The conditional mean spectra by disaggregating the eta spectral shape indicator
摘要： Conditional spectra are a recent development in this field, which utilizes the advantages of spectral shape indicators, for example, epsilon and eta. The application of an eta indicator in conditional spectra calculations depends mainly on calculating the peak ground velocity epsilon, data about which are not readily available in the current literature. This issue has been solved by linear regression between the conventional epsilon and the peak ground velocity epsilon. However, not enough attention has been paid in the literature to the disaggregation of the eta indicator. For this reason, the disaggregation of seismic hazard based on the use of an eta indicator has been investigated in this paper, based on a simplified linear seismic source. The obtained results were compared with the available approach in the literature, which shows that this refinement has a meaningful effect on the conditional spectra specifically in the short period range. Furthermore, eta‐based conditional spectra are used at different hazard levels to select ground‐motion records. A three‐storeyed building is then analysed, and the corresponding annual probability of failure is calculated based on the full dataset as well as on the records, which were selected based on conditional spectra.
关键词： genetic algorithm,eta,seismic hazard analysis,ground‐motion prediction equation (GMPE),epsilon
更新于2025-09-23 15:23:52
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A high gain miniaturised patch antenna with an epsilon near zero superstrate
摘要： In this paper, a miniaturized patch antenna (MPA) with Zero Index Metamaterial (ZIM) as Superstrate at 518MHz is designed and fabricated. The proposed method is utilized for retrieving the effective properties, i.e., impedance, refractive index, as well as the permittivity, and permeability of the unit cell. We have investigated the effect of distance between the antenna and the Superstrate on performance of the antenna. Moreover, the performance of the antenna is evaluated by both simulations and measurements. The results of our study have shown more directional and higher gain patch antennas. Also, a good agreement between the measured and the simulation values is found. It is demonstrated that the gain of antenna, having the ZIM Superstrate, is much higher compared to the one without the ZIM superstrate. Furthermore, the mean value of the gain for the proposed Metamaterial antenna (which is Superstrate-based) is considerably improved from -1.9 to 3.97 dBi comparing to the patch antenna alone. In fact, the directivity of the antenna is dramatically improved based on the zero refraction properties of the Metamaterial.
关键词： Low profile,Metamaterial,Epsilon near zero material,High gain antenna
更新于2025-09-23 15:23:52
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Microstrip Line Impedance Matching Using ENZ Metamaterials, Design and Application
摘要： The idea of this paper is to extend the tunneling effect of epsilon-near-zero (ENZ) narrow channel for matching two microstrip lines with different impedance characteristics. The main advantage of this method is the possibility to design a channel with subwavelength electrical size and obtain similar matching condition when compared with a conventional λ/4-transformer. The bandwidth of the structure is directly related to the bandwidth of the ENZ-metamaterials (MTM). The suggested matching circuit is comprised of a metallic wall and an ENZ narrow channel. To realize the ENZ channel, a rectangular waveguide which operates in TE10 mode is designed and implemented using a substrate integrated waveguide (SIW) technology. A set of vias are also needed for emulating the metallic wall to reduce the ENZ channel cross section. The proposed structure for different impedance values of 50?, 100?, and 150? was designed, simulated, fabricated, and tested. Moreover, as an important application of a matching network, a microstrip patch antenna has been matched over the desired frequency band. Simulation results based on CST microwave studio have good agreement with measurements. It is shown that the bandwidth of the circuit is 8%–15%.
关键词： impedance matching,metamaterials (MTM),Epsilon-near-zero (ENZ),microstrip line,tunneling
更新于2025-09-23 15:22:29
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Electromagnetic wave cloaking and scattering around an antiresonance-resonance symmetrical pair in the frequency domain
摘要： Cloaking and scattering cancellation of electromagnetic waves have attracted much attention since they allow control of rf and light waves and are of scientific interest. The analytical results demonstrated in this paper reveal that plasmonic cloaking, which is one of the schemes for scattering cancellation, occurs in the vicinity of Tonks-Dattner resonances in the frequency domain, where resonances enhance wave scattering. This antiresonance-resonance pair for cloaking and scattering is cross-correlated by the symmetrical locations above and below the electron plasma frequency, respectively. However, the cloaking effect is almost independent of electron collisions with neutral particles, whereas scattering at resonance is fairly sensitive to them, leading to unclear resonance. An experimental verification of this analytical prediction is performed for the cloaking effect on working points passing through the cloaking condition and approaching resonance, which is dynamically controlled by changing the electron density. Numerical calculations based on a model configuration similar to the experimental setup confirm scattering cancellation and an increase in scattering as the points get close to the resonance condition. These results are direct evidence of scattering cancellation with a uniform epsilon-near-zero material and demonstrate the effectiveness of plasma as a cloaking material.
关键词： plasma,electromagnetic cloaking,scattering cancellation,Tonks-Dattner resonances,epsilon-near-zero material
更新于2025-09-23 15:22:29
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Coupling between plasmonic nanohole array and nanorod arrays: the emerging of a new extraordinary optical transmission mode and epsilon-near-zero property
摘要： The compound Ag nanohole structures with an Ag nanorod in the middle of an Ag nanohole are investigated by finite-difference-time-domain calculations. The structure shows strong polarization-dependent optical properties. A new extraordinary optical transmission (EOT) mode is observed when the polarization direction is aligned with the long axis of the nanorods, and its resonance wavelength red-shifts exponentially with the nanorod length. Around this resonance wavelength, the real part of the effective permittivity also becomes zero, demonstrating the epsilon-near-zero (ENZ) property. The new EOT mode is found to be the result of the enhanced local radiation of the nanorods as well as the electromagnetic coupling to the nanoholes to produce the enhanced transmission. The tunable resonance wavelength, EOT, strong near-field enhancement, and ENZ properties make the structure ideal for many potential applications, such as ultrathin optical filter, polarizers, surface-enhanced spectroscopies, etc.
关键词： tunable transmission,epsilon-near-zero,nanohole array,extraordinary optical transmission,nanorod array
更新于2025-09-23 15:21:01
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Epsilon-near-zero medium for optical switches in Ho solid-state laser at 2.06????m
摘要： Indium tin oxide (ITO), an epsilon-near-zero material in the low-dimensional family, was successfully fabricated and first used as an optical switcher in 2.06 μm. In the Tm:fiber pumped passively Q-switched laser, a maximum average output power of 312 mW was obtained with a shortest pulse width of 2.42 μs and a repetition rate of 20.53 kHz, corresponding to a single pulse energy and a peak power of 15.20 μJ and 6.28 W, respectively. Results suggest that ITO is looking forward to develop into a kind of suitable saturable absorber for generation of nanosecond pulse in solid state lasers.
关键词： Passively Q-switched,Optical switch,Indium tin oxide,Epsilon-near-zero,2.06 μm
更新于2025-09-23 15:19:57
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Tailoring absorption spectrum by inserting an epsilon-near-zero film into metal-dielectric-metal assembly
摘要： A method of tailoring the absorption band generated by metal-dielectric-metal (MDM) resonator is analytically proposed and numerically investigated in this paper. By inserting an epsilon-near-zero (ENZ) ?lm into the MDM layers, the absorption bandwidth can be su?ciently widened due to the coupling from ENZ mode to localized edge plasmon mode. Theoretical instructions of how to design respective layer thickness to obtain optimized absorption rate are investigated with the guidance of vast simulations and the hybrid resonance characteristics by the coupling from ENZ mode are further inspected by monitoring the resonant electric and magnetic ?eld. The meta-absorber can achieve high absorption with a large bandwidth under oblique incidence. The method and the structure proposed in this paper have potential views in highly integrated nanostructures in solar cells, photovoltaic and sensing application ?elds.
关键词： Epsilon-near-zero (ENZ),Absorber,Metamaterial
更新于2025-09-23 15:19:57
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Effect of Aberrations in Femtosecond Laser Writing Using the Phase Mask Technique
摘要： The impedance plethysmography (IP) has long been used to monitor respiration. The IP signal is also suitable for portable monitoring of respiration due to its simplicity. However, this signal is very susceptible to motion artifact (MA). As a result, MA reduction is an indispensable part of portable acquisition of the IP signal. Often, the amplitude of the MA is much larger than the amplitude of the respiratory component in the IP signal. This study proposes a novel filtering method to remove the high-amplitude MA’s from the IP signal. The proposed method combines the idea of ε-tube loss function and an autoregressive exogenous model to estimate the MA while leaving the periodic respiratory component of the IP signal intact. Also, a regularization method is used to find the best filter coefficients that maximize the regularity of the output signal. The results indicate that the proposed method can effectively remove the MA, outperforming the popular MA reduction methods. Several different performance measures are used for the comparison and the differences are found to be statistically significant.
关键词： epsilon-tube,impedance plethysmography,portable monitoring of respiration,motion artifact reduction,Autoregressive exogenous model
更新于2025-09-19 17:13:59
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A Designed Broadband Absorber Based on ENZ Mode Incorporating Plasmonic Metasurfaces
摘要： In this paper, we present a numerical study of a metamaterial absorber that provides polarization-insensitive absorption over a broad bandwidth of operation over the mid-infrared region. The absorber consists of a periodically patterned metal-dielectric-metal structure integrated with an epsilon-near-zero (ENZ) nanolayer into the insulating dielectric gap region. Such an anomalous broadband absorber is achieved thanks to a couple of resonant modes including plasmon and ENZ modes that are excited under mid-IR light illumination. By adding a 0.06-μm-thick ENZ layer between the patterned gold rectangular grating and the SiO2 dielectric layer, the absorber captures >95% light over a 1.5 μm bandwidth centered at a near-8-μm wavelength over a wide range of oblique incidence under transverse-magnetic and -electric polarizations. The designed ENZ-based wideband absorber has potential for many practical applications, including sensing, imaging and solar energy harvesting over a wide frequency regime.
关键词： wideband absorber,plasmon mode,Brewster mode,epsilon-near-zero
更新于2025-09-19 17:13:59