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We present a novel approach for actively controlling electromagnetically induced transparency (EIT) analogs in a single-mode microstrip cavity. This cavity is side-coupled with a pair of varactor-loaded split-ring resonators (SRRs). The EIT-like effect is achieved through resonance hybridization between the paired SRRs with frequency detuning. The microstrip cavity is utilized to enhance the EIT-like transmission properties, including Q-factor and group delay. Varactor diodes, soldered at the gap of the SRRs, are biased electrically through a DC voltage source. This dynamic modulation setup allows for the tuning of the enhanced EIT analog. Experimental results demonstrate that the enhanced EIT-like transmission spectrum can be tuned reversibly by 378 MHz with respect to the transmission dip frequency of 2.464 GHz under the bias voltage ranging from 0 to 5 V. Simultaneously, the controlled transmission spectrum enables a remarkable change in group delay of 10.9 ns. Moreover, the modulation amplitude of the composite SRRs-cavity structure reaches a peak value of up to 34.5 dB, significantly higher than the 6.4 dB of the individual SRRs pair. These results hold promise for inspiring innovation in actively controlled photonic devices for practical applications. [ABSTRACT FROM AUTHOR]

Magnetic skyrmioniums—with a composite structure comprising two skyrmions with opposite topological charges, exhibit unique dynamic behaviors that are crucial for technological advancements and have application potential for high-density and nonvolatile memory. This study explores the impact of periodic perpendicular magnetic anisotropy (PMA) and damping gradients on skyrmioniums. Utilizing the object oriented micromagnetic framework for detailed simulations, the effective control and enhancement of the skyrmionium stability and mobility through the periodic modulation of PMA and damping gradients is demonstrated. The results demonstrate the dynamic behavior and stability control of skyrmioniums in periodic PMA/damping gradient nanowires. Moreover, the critical influence of the periodic gradient on the skyrmionium motion and stability is highlighted. The results present new avenues for developing advanced memory technologies, leveraging skyrmionium's unique nonlinear behaviors to improve the device performance and reliability. [ABSTRACT FROM AUTHOR]

In this paper, a homogenized multiphase lattice Boltzmann (LB) model is established for parallelly simulating immiscible two-phase flow in both solid-free regions (pore scale) and porous areas (continuum scale). It combines the color-gradient multiphase model with the Darcy–Brinkman–Stokes method by adding a term that includes surface force and drag force of porous matrix to multiple-relaxation-time LB equation in moment space. Moreover, an improved algorithm is proposed to characterize and implement the apparent wettability in the locally homogenized porosity field. Validations and test cases are given to demonstrate the accuracy and robustness of this new model, as well as its applicability for trans-scale fluid simulation of transport and sorption behavior from porous (Darcy flow) area to free (Stokes flow) area. For practicality, the two-phase seepage flow in a composite rock structure with multiscale pores is simulated by this new model, and the effects of viscosity ratio and wettability on the displacement process are discussed. [ABSTRACT FROM AUTHOR]

In order to solve the problems of low energy utilization and poor structural stability of photothermal conversion materials, a graphene-based photothermal conversion material was prepared, which was structurally integrated with a light-absorbing upper layer and a heat insulating base. During the preparation process, a tightly arranged nanotube array upper layer was constructed on the basis of graphene films by microimprinting technology, and a porous aerogel base was molded by a fixed-point titration and multiple-foaming method. The results show that the light trap constructed from graphene hollow nanotubes can significantly increase the number of light reflections and reduce light reflectivity. Meanwhile, the length of the nanotubes is directly proportional to the light-absorbing capacity of the material, which can increase the light-absorbing rate to more than 98% under the embossing conditions of 85 kN and 8h. In addition, the porous aerogel insulation base can effectively improve the photothermal conversion effect, and a photothermal conversion efficiency of 87% and a water evaporation rate of 1.3 kg/(m2 h) can be achieved at a base thickness of 6 mm. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiFe 2 O 4 /CeO 2 composites with the optimal Ce concentration were synthesized. • The unique structure allows the material to maximize the exposure of the active sites. • The oxygen vacancy introduced by CeO 2 can improve the conductivity of the catalyst. • The oxygen vacancy and the composite cooperate to achieve great catalytic performance. The development of efficient catalysts to accelerate the three-phase reaction at the cathode side represents a crucial step in enhancing the performance of lithium-oxygen batteries (LOBs) with high energy density. In this study, NiFe 2 O 4 /CeO 2 composites with an appropriate Ce concentration were prepared as cathode catalysts for LOBs, and the unique micro-flower structure maximally exposed the active sites of the materials. The catalyst cleverly integrates the excellent oxygen evolution reaction (OER) activity of NiFe 2 O 4 and the outstanding oxygen reduction reaction (ORR) activity of CeO 2. The high concentration of oxygen vacancies and the composite structure synergistically enhanced the charge transfer ability, altered the charge distribution of the active sites, and modulated the electronic structure of the material, thereby achieving an appropriate adsorption energy for oxygen-containing intermediates. Consequently, the composite material displays 343 stable cycles, a round-trip efficiency of 97.8 %, and a discharge specific capacity of 7478 mAh/g. Additionally, it exhibits fast charging and slow discharging capabilities for up to 726 h. This work offers insights into the design of efficient bifunctional cathode catalysts for LOBs. [ABSTRACT FROM AUTHOR]

A new type of lead-free perovskite Cs 3 Bi 2 Br 9 nanocrystal (NCs) was synthesized by thermal injection method at 190 °C, according to X-ray diffraction and theoretical analysis, the Cs 3 Bi 2 Br 9 NCs belongs to the monoclinic system C 12/ c 1. We report for the first time that the luminescence intensity of broad-peak-emitting Cs 3 Bi 2 Br 9 is significantly improved by doping with K+, and the full-width at half maximum (FWHM) of sample Cs 3 Bi 2 Br 9 :0.2K+ is 124 nm. Herein, the stability of Cs 3 Bi 2 Br 9 :xK was monitored and found to have excellent environmental stability, thermal stability, and photostability. In addition, Cs 3 Bi 2 Br 9 :0.2K was coated outside Sr 2 MgSi 2 O 7 :Eu2+,Dy3+ (SMS) to form a core-shell structure composite material Cs 3 Bi 2 Br 9 :0.2K+/SMS@SiO 2 and achieved fine tuning of the afterglow color. This work increases the luminescence intensity of Cs 3 Bi 2 Br 9 by ion doping and exhibits excellent stability, in addition to the cladding of lead-free perovskites with long afterglow materials provides a new application strategy for lead-free perovskites. [ABSTRACT FROM AUTHOR]

[Display omitted] The lack of stable anode materials with high capacity and fast redox kinetics has hindered the application of lithium-ion batteries (LIBs) for energy storage. Metal-phase molybdenum disulfide (1T-MoS 2) is recognized as a promising energy storage material because of its combination of excellent physical and electrochemical properties. In this paper, we report the insertion of ammonium ions (NH 4 +) into the MoS 2 interlayer and effective complexation with graphene oxide (GO). The MoS 2 layer spacing was effectively enlarged from 0.67 nm to 1.1 nm by NH 4 + insertion, and this method not only maintains the stability of the 1T phase and reduces the energy barriers for Li+ insertion and de-embedding, but also improves the diffusion kinetics of Li+. The Li+ diffusion coefficients of the prepared 1T-MoS2/G composites were confirmed to be enhanced by three orders of magnitude by constant current intermittent titration technique tests. Compared with the conventional preparation method, the mechanism of action of NH 4 + insertion provides a new regulation strategy. In addition, electrochemical studies showed that the specific capacity of the prepared 1T-MoS2/G electrode was 1533 mAh/g for 180 cycles at 0.1 A/g and 1679 mAh/g for 800 cycles at 0.5 A/g. Thus, the strategy of introducing NH 4 + intercalation to improve the cycling stability of MoS 2 raises the prospect of practical application of layered metal sulfide anodes. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) boron-containing materials hold great promise for energy storage applications due to their unique characteristics. These materials feature a porous structure, are lightweight, possess a large surface area, and exhibit high thermodynamic stability. These attributes collectively make them highly suitable for various energy storage solutions. A newly identified structure, B14, exhibits excellent chemical stability and possesses most of these desirable properties, making it an ideal candidate for energy storage. To further enhance hydrogen storage capacity, we propose a novel composite structure by incorporating Li atoms into B14. In this study, we investigated the B14 monolayer decorated with Li using first-principles calculations. We found that Li atoms can be stably anchored on B14 with an adsorption energy of −2.73 eV. Additionally, Li atoms transfer some of their 2s electrons to B14, creating significant electropositivity. These metallic sites can polarize the adsorbed hydrogen molecules, and the corresponding electrostatic interactions between them can be strengthened. Each Li@B14 supercell can adsorb up to 40 H 2 molecules, resulting in a storage capacity of 11.2 wt%, which significantly exceeds the U.S. Department of Energy (DOE) target of 5.5 wt%. The average adsorption energy between −0.337 eV/H 2 and −0.211 eV/H 2 is suitable for reversible hydrogen storage at room temperature. This study highlights the potential of metal-decorated B14 for hydrogen storage, paving the way for further advancements in this field. [Display omitted] • Li atoms can be stably decorated onto the B14 monolayer. • Li@B14 monolayer was investigated for reversible hydrogen storage. • The hydrogen-storage capacity of Li@B14 monolayer can reach to 11.2 wt%. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on the quasi-static indentation performance of polyurethane (PU) foam-filled carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) corrugated sandwich composite structures (SCSs) under different indenter tip geometries (conical, trapezoidal, hemispherical, pyramidal, and cylindrical shapes). The SCSs were produced using hybrid manufacturing methods: (1) the facesheets were fabricated using the vacuum-assisted resin infusion (VARI) process, (2) the CFRP and GFRP corrugated cores were additively manufactured using the fused filament fabrication (FFF) process, and (3) the self-expanding PU foam-filled the open spaces in the core. The results elucidated that the indenter tip geometry and core material have a large influence on the indentation performance of SCSs. The cylindrical indenter showed the highest peak load, bending stiffness, and damage severity, while the conical indenter offered the lowest peak load, energy absorption, and damage severity. Among different core materials, CFRP corrugated core SCSs exhibited higher peak loads, specific energy absorption, and damage severity compared to ones with GFRP core. The primary damage modes were observed using an optical microscope, showing facesheet rupture, debonding between facesheets and core, core crushing, foam densification, and shear plugging. Shear plugging is a unique failure mode observed with cylindrical indenter tip geometry due to the blunt edges of the indenter, which induced large damages in SCSs. These findings provide new insight into the design and development of lightweight additively manufactured SCSs, which will benefit a wide range of industries and applications. [ABSTRACT FROM AUTHOR]

Recyclable, lightweight materials using advanced processing techniques are essential for the sustainable development of future wind turbine blades. Thermoplastic composite sandwich structures were developed to satisfy this need. This study presents a novel continuous approach for fabricating recoverable fully thermoplastic composite honeycomb sandwich structures. Finite element models of the honeycomb and sandwich plate, accounting for surface-to-surface contact between cells, were developed. Uniaxial compression analysis was performed on honeycombs to investigate their failure modes and energy absorption characteristics. Furthermore, the deformation mode and load-bearing capacity of thermoplastic composite honeycomb sandwich panels were examined under out-of-plane compression and shear loads. Our comprehensive finite element model, incorporating the intricate contact behavior of individual cells, demonstrated a remarkable concordance with experimental outcomes. Insightful predictions were given regarding the correlation between contact areas and load-bearing capacities. [ABSTRACT FROM AUTHOR]

This study reports a two-dimensional bi-directional E-glass woven fabric preform structure is converted into a three-dimensional sandwich composite structure with the help of wooden molds and matrix material. One to three levels of sandwich composite are prepared with a rectangular core configuration by keeping the specimen's constant dimensions. A second multilevel sandwich composite sample set is developed with hexagonal, square, and triangular core configurations, maintaining length, width, height, and weight constant. The developed composite samples are characterized by their compressive properties. For single, double, and triple-level sandwich composites with rectangular cores, it is found that increasing the number of levels led to an increase in compressive load capacity, with triple-level structures exhibiting the highest strength. However, an increase in the number of levels resulted in a decrease in specific compressive load. Additionally, the energy absorption capacity increases as the number of levels increases. In the case of multilevel sandwich composites with triangular, square, and hexagonal core, the triangular core demonstrated the highest compressive strength and energy absorption capacity compared to square and hexagonal configurations. The failure modes of the sandwich composite structure have also been discussed. The results indicate that the sandwich composite's compressive, energy absorption properties, and failure modes depend on many parameters, such as the number of levels, core structure, free wall length, face sheet length, and loading direction. The findings of this study will provide valuable insights into potential applications and performance of these advanced sandwich structures, enabling improved design and optimization for specific engineering applications across diverse industries. [ABSTRACT FROM AUTHOR]

To overcome the drawbacks of traditional electromagnetic acoustic transducers (EMATs) that depend on mechanical scanning, adding to both cost and complexity, this study introduces a sector scanning imaging method utilizing Electromagnetic Ultrasonic Shear Vertical (SV) waves. A simulation model for EMAT was developed, optimizing through variable frequency and unidirectional line focusing coils. The simulation revealed that a novel composite magnetic structure significantly enhanced the magnetic flux density to 1.318 T, a 159.44% increase over conventional magnets, leading to a 102.08% rise in ultrasonic signal intensity and a marked improvement in the signal-to-noise ratio. By converting echo signal time data into spatial coordinates, the technology enables high-resolution defect imaging. The variable frequency-EMAT (VF-EMAT) technique accurately identified defects, with minor discrepancies from actual defect centers, showcasing its precision. The unidirectional line focusing-EMAT (ULF-EMAT) method further improved defect detection accuracy and shape restoration. However, the technique's reliance on the main-pulse limits its ability to detect near-surface defects, suggesting an avenue for future research. [ABSTRACT FROM AUTHOR]

[Display omitted] A composite material with a high potential for absorbing electromagnetic waves (EMW) was obtained by selecting poly (vinylidene fluoride) (PVDF) as the matrix, MXene as the conductive filler, and cobalt ferrite (CoFe 2 O 4) as the magnetic filler. A layer-by-layer assembly strategy involved hot pressing and sequential blade coating, followed by vapor-induced phase separation, was used to implement the preparation of PVDF/MXene/CoFe 2 O 4 (PMC) composites. The process facilitates the formation of a well-organized multilayer porous framework, providing a gradient of positive conductivity, negative magnetism, and porosity within the composites. Incorporating distinct multilayer, porous, and gradient structures into a single composite led to exceptional impedance matching (Z), with an area percentage of up to 8.4 % in the optimal range of 0.8 to 1.2. Furthermore, the multiple interfaces formed by the various components, multilayer structure, and porous configuration significantly enhanced the EMW attenuation capability, with the attenuation constant reaching as high as 274. Consequently, the PMC composite demonstrated outstanding performance with a minimal reflection loss (RL min) of −56.5 dB, a specific RL min of 23.5 dB/mm, and the broadest effective absorption bandwidth of 3.2 GHz. The combination of the competitive EMW absorption capability, low density, flexibility, adequate tensile strength, and amphiphilic Janus surface may significantly broaden the application scenarios of PMC composites. [ABSTRACT FROM AUTHOR]

Based on the elaborate 3D solid finite element (FE) model established by ABAQUS software, a pseudo-static analysis was conducted on a special-shaped concrete-filled steel tubular column composite frame structure. The FE model considers the confinement effect of both the steel tubes and the tensile bars exerting on the core concrete. The results of the numerical analysis concerning failure modes, load-displacement hysteretic curves, load-displacement skeleton curves and stiffness degradation-displacement curves demonstrate a strong correlation with the existing quasi-static test data. Furthermore, an in-depth analysis was conducted on the impact of the axial compression ratio of column on the plastic energy dissipation distribution mechanism. With an axial compression ratio of the column ranging from 0.1 to 0.55, the composite frame structure primarily relies on the energy dissipation of beams, while the columns serve as supplementary support, thereby exemplifying the principle of "strong column-weak beam." As the axial compression ratio rises to the range of 0.6–0.8, the composite frame structure transitions a "strong beam-weak column" structural system. Combined with the longitudinal compressive strain of the steel tube at the bottom of the column, a quantitative evaluation method for seismic damage is proposed, grounded in indexes of "stiffness damage" and "energy damage." Then, the threshold values of energy damage and stiffness damage are determined across four distinct levels: "elastic stage in small earthquake," "elasto-plastic stage in medium earthquake," "plastic stage in heavy earthquake" and "failure stage." The proposed method effectively evaluate the damage severity of special-shaped CFT column composite frame structure subjected to seismic events. Highlights: The FE model in this paper has high accuracy, which can reasonably simulate the pseudo-static behavior of special-shaped CFT column composite frame structure. A seismic energy dissipation analysis method of special-shaped CFT column composite frame structure is proposed, and the influence of axial compression ratio on the energy dissipation distribution mechanism of beams and columns is further analyzed. This paper propose two indexes, namely "stiffness damage" and "energy damage," which can reflect the internal properties of composite frame structure and can accurately evaluate the damage degree of composite frame structures. [ABSTRACT FROM AUTHOR]

The problem considered in the present paper has its origins in the description of a laminated structure consisting of an adhesive layer and two adherents. The problem of deformation of the layered structure is described by the coupled model of linear and strain gradient elasticity. Namely, we assume that deformations of both the adhesive layer and adherents obey antiplane shear models, but, at the same time, the adhesive layer is described by the simplified strain gradient elasticity theory (or, in other words, the so-called one-parameter gradient elasticity theory), while the adherents obey the classical elasticity theory. The shear moduli of the adhesive layer and its width depend on a small parameter. We investigate the limiting passage, as this parameter tends to zero. As a result, we find out the five types of limit models with imperfect interfaces in dependence of the parameter exponent. Three of them are the same as in the classical theory, while two of them are new and essentially belong to the strain gradient elasticity. [ABSTRACT FROM AUTHOR]

Inspired by the remarkable energy absorption and damage tolerance capabilities observed in mantis shrimp crustaceans, this study delves into the intricate realm of biological composites with helicoidal structures. However, the effect of the relative orientation of fibers within the helicoidal structure matrix on the buckling and vibration characteristics still warrants comprehensive investigation for the better design of the bioinspired structures. For the first time, a Non-Uniform Rational B-Splines (NURBS)-based isogeometric analysis (IGA) framework termed NURBio is proposed to investigate the vibration and buckling characteristics of bioinspired laminated composite structures. The framework employs NURBS basis functions for exact complex geometric representation and field approximation and offers superior computational accuracy and efficiency as compared to conventional finite element method (FEM). The present analysis is underpinned by an inverse hyperbolic shear deformation theory (IHSDT) capable of accurately capturing the interlaminar stress distribution. This research investigates the performance of various bioinspired layup configurations encompassing recursive, exponential, semicircular, and Fibonacci helicoidal designs and compares them with those of unidirectional, and cross-ply laminates. A series of numerical examples on the buckling and vibration response of bioinspired composite plates are presented to demonstrate the versatility and efficacy of the proposed isogeometric framework. The influence of different layups, loading and boundary conditions, and geometric properties on the response of different bioinspired plate structures are meticulously examined. The study offers valuable insights into the design and optimization of high-performance bioinspired structures. [ABSTRACT FROM AUTHOR]

Shearing would occur in the interface of asphalt overlay on existing rigid airport pavements due to the differences in the mechanical properties of the materials loaded by aircraft. The interlayer contact affects the mechanical characteristics of the asphalt overlay directly. Nevertheless, effective interlayer relative displacement obtained accurately by the existing displacement sensors of the loading apparatus remains challenging. This study aimed to use digital image correlation technology to obtain effective interlayer relative displacements and enhance the accuracy of interfacial contact parameters. Composite structure specimens were prepared, and the fixture for interlayer shear tests was designed and fabricated. Then, the digital image recognition scheme for the required markers was designed and optimized. The effective interlayer relative displacement values were obtained by image recognition and calculation of surface markers on the specimens. Finite-element simulations validated the mechanical response of the composite specimens with interlayer shearing. The results indicated that the optimized marking approach using the wall mending agent for surface application and color coding enhanced the image recognition quality of marking points on the specimen surface. Further image extraction provided effective interlayer relative displacement values in interlayer shear, thereby improving the accuracy of the interface contact parameters. For the composite structure specimens utilizing styrene-butadiene-styrene (SBS) modified asphalt as the tack coat, the corresponding maximum interlayer shear stress strength was 0.6 MPa, and the fracture energy was 2,917 J/m2. This research provides valuable insights for investigating the impact of interlayer contact in composite pavement structures on the mechanical characteristics of asphalt overlay. [ABSTRACT FROM AUTHOR]

In this research work, an axially functionally graded (AFG) Nano-composite beam is modeled to observe the free vibration behavior beamfor non-uniform geometry. The beam is mathematically modeled as an Euler-Bernoulli beam using MATLAB code. Where the graphene Nanoplatelets (GPL) are axially reinforced with A and V type functions. The geometry nonuniformity in the beam is introduced with an exponential function, where the exponent of the equation governs the cross-section of the geometry. The material modulus and other properties at each section along the beam axis are modeled as particulate fiber randomly oriented composite with the help of Halpin Tsai theory and rule of mixture. The finite element method (FEM) is used for the solution and analysis of the model. The model is first validated for uniform geometry results then the non-dimensional fundamental frequency of the AFG beam is obtained for various parameter combinations. The results for various combinations are plotted and it is noted that the free vibration characteristic of the model is strongly dependent on non-uniformity in geometry, end-support constraints,and slenderness ratios (L/h0) combination of the model. This research contributes significantly to the understanding of advanced composite structures and offers potential benefits for the design and optimization of these materials in various engineering applications. The study reveals significant variations in natural frequencies depending on the A type & V type GPL distribution pattern and geometric parameters, which are crucial for the structural integrity and performance of nano composite beams. [ABSTRACT FROM AUTHOR]