Search Results (2,064)

This paper innovatively proposes a high-precision fabrication strategy for silicon-based micro–nano-composite layered structures composed of micron-scale platforms and nanopillars, effectively addressing the challenges of alignment errors and material mismatch during manufacturing. By integrating electron beam lithography (EBL), inductively coupled plasma (ICP) etching, and ultraviolet nanoimprint lithography (NIL) into a unified multi-step workflow, the method achieves exceptional precision and efficiency in producing complex micro–nano-composite architectures. Comprehensive structural characterization is performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), with probe convolution effects carefully corrected to ensure accurate dimensional analysis. Experimental results confirm the outstanding stability and uniformity of the fabricated structures, exhibiting minimal deviations in both feature size and spatial layout. Nanopillars with diameters ranging from 50 to 200 nm are successfully integrated onto 1-µm square platforms, with the lateral deviation of 50 nm features maintained within 5% or less. Furthermore, the method effectively mitigates thermal stress-induced misalignment during the fabrication of multi-material layers, demonstrating strong potential for scalable production of advanced photonic devices and integrated nanophotonic systems. Overall, this work establishes a robust and versatile technical pathway for the precise manufacturing and quantitative characterization of micro–nano-composite structures, providing a key foundation for the next generation of photonic integration technologies. Full article

This study investigated the electrolytic-plasma hardening (EPH) of cast 20GL steel, used for railway spring beams. The main objective was to analyze the spectral characteristics of the cathodic discharge and establish correlations between the plasma parameters, processing regimes, and resulting surface properties. Optical emission spectroscopy revealed that the plasma at 260 V exhibited a high-energy state with an electron density of ~5.3 × 10¹⁶ cm⁻³ and an electron temperature of 10,031 K. Using these parameters, the heat flux from the plasma to the steel surface was estimated at ~1.5 × 10⁷ W/m², confirming that the discharge provides sufficient energy for surface austenitization. Microstructural analysis demonstrated that the electrolyte flow rate, which determines the cooling rate, is the key parameter controlling phase transformations. At low flow rates, ferrite–pearlite and bainitic structures formed, while a fully martensitic structure and maximum hardness (1046 HV) were achieved at 10 L/min. Tribological tests confirmed the superior wear resistance of the martensitic layers, showing a friction coefficient of 0.454 and a wear volume 3.4 times lower than in the as-cast state. These findings verify that EPH offers an energy-efficient, low-cost method for improving the surface performance and service life of 20GL steel components in heavy-duty railway applications. Full article

The objective of this study was to investigate electron beam hardening (EBH) technology and compare its performance with laser beam hardening (LBH) in the context of manufacturing components such as gears, which increasingly employ submicron bainitic steels. Given the stringent demands for durability and fatigue resistance of gear teeth, identifying an optimal surface hardening method is essential for extending service life. Comprehensive analyses, including light and electron microscopy, hardness testing, tribocorrosion testing, and X-ray diffraction for phase composition, were conducted. The EBH-treated layer exhibited a slightly higher hardness (by 26 HV) compared to the LBH-treated layer (average 654 HV), while the base material measured 393 HV. The EBH process produced a uniform hardness distribution with a subsurface zone of reduced hardness. In contrast, LBH resulted in a surface oxide layer absent in EBH due to its vacuum environment. Both techniques reduced the residual austenite content in the surface layer from 22.5% to approximately 1.3%–1.4%. Notably, EBH achieved comparable hardening effects with nearly half the energy input of LBH, demonstrating superior energy efficiency and industrial feasibility. Application of the developed EBH process to an actual gear component confirmed its practical potential for modern gear manufacturing. Full article

Recycling rubber and steel fibers from end-of-life tires for use in structural concrete presents a sustainable pathway to improve resource efficiency and reduce environmental impact. This study assesses the shear performance of reinforced concrete beams in which shredded tire rubber substitutes 20 vol.% of both fine and coarse natural aggregates. The effect of including recycled tire steel fibers (RSF) and industrial steel fibers (ISF), each at a dosage of 20 kg/m³, is also examined. The experimental program involved testing twenty-four cylindrical specimens and seven reinforced concrete beams to evaluate the mechanical and structural behavior of the proposed mixtures. A novel layered concrete configuration is also evaluated, in which rubberized (RU) concrete or steel fiber reinforced rubberized (RUSF) concrete is placed in the tensile zone, and plain (P) concrete is placed in the compressive zone. The results indicate that rubber incorporation alone reduces shear strength by 30.9% compared to P concrete. However, the inclusion of steel fibers not only compensates for this reduction but significantly improves strength and ductility. Beams fully cast with RUSF concrete exhibit a 31.9% increase in shear strength compared to P concrete. In contrast, layered beams with RUSF concrete in the bottom and P concrete in the top show a comparable performance. These findings highlight the potential of integrating steel fiber reinforced rubberized concrete and functional layering to enable the use of substantial quantities of recycled tire materials without compromising structural performance, offering a promising solution for eco-efficient construction. Full article

This paper introduces a novel design of a circularly polarized (CP) beamforming antenna that is capable of shaping the original beam into a flat-top configuration. Upon loading a metallic ring, the beamforming pattern can transition into an isoflux pattern. The proposed compact lens antenna comprises a multi-layer honeycomb-like unit lens structure, with a patch and support platform situated beneath the lens. Positioned above the lens, a loadable metallic ring is employed to assist in beamforming. Through a specially designed dielectric lens structure, the lens can control the radiation of electromagnetic waves to achieve the desired beam pattern, while the loadable metallic ring plays a role in optimizing the field across the aperture plane of the lens. This work utilizes a multi-port feed network to drive the patch. To validate the proposed antenna design method, a prototype is fabricated for measurement. The measured result is nearly identical to the simulated result. Within the frequency range spanning from 4.8 GHz to 5.2 GHz (which represents a 10% bandwidth), the antenna demonstrates effective beamforming ability and achieves effective pattern switching. This renders it a promising candidate for scenarios where uniform signal strength coverage is required. Full article

Multi-slice mining of the 70 m ultra-thick coal seam in East Junggar coalfield, China is marked by large-scale mining space expansion and frequent stress disturbances. To address those, this study uses theoretical analysis, physical simulation, and numerical simulation to explore the evolution of an overburden bearing structure and the control of strata behavior in multi-slice mining. The results (1) clarify the overburden fracture-hinging characteristics: fractured blocks in lower hard strata form beam-type hinges (early stage), the lower hinged structure weakens and the beam-type hinge structure moves upward in steps (middle stage), the continuous increase in the mined-out space leads to the transverse O-X fracture of far-stope rock strata, and broken rock blocks are extruded into shells (late stage); this study also proposes an identification method for the morphology of roof bearing structures (including beam structure, higher beam structure, and arch structure); (2) define the support-controlled strata range and load calculation method at different stages, and show that the support load “increases slowly under the near-stope roof bearing structure and tends to stabilize under the far-stope roof bearing structure” as the roof bearing structure moves upward; and (3) guided by the aims of avoiding cantilever beams and ensuring near-stope roof stability, lead us to propose the following measures: pre-splitting main roof (early stage); short working faces with reduced layered thickness and rapid advance (late stage); and goaf/separation grouting (whole process). The maximum support load drops from 20,017.5 kN to 16,192.5 kN, enabling lightweight support selection. This study provides theoretical guidance for support selection and roof control in the multi-slice mining of ultra-thick coal seams. Full article

Integrated Sensing and Communication (ISAC)-enabled Roadside Units (RSUs) encounter significant performance trade-offs between target sensing and multi-user communication in complex urban environments, where conventional optimization methods are prone to converging to local optima and joint optimization methods often yield sub-optimal results due to conflicting objectives. To address the challenge of trade-off between sensing and communication performance, this paper proposes a hierarchical beamforming optimization solution designed to tackle joint sensing–communication problems in such scenarios. The overall optimization problem is decomposed into a two-level “leader-follower” structure. In the leader layer, we introduce a max–min strategy based on the bisection method to transform the non-convex Signal-to-Interference-plus-Noise Ratio (SINR) optimization problem into a second-order cone constraint problem and solve the communication beamforming vector. In the follower layer, the Signal-to-Clutter-plus-Noise Ratio (SCNR) maximization problem is converted into a Semi-Definite Programming (SDP) problem solved via the CVX toolbox. Additionally, we introduce a “spatiotemporal resource isolation” mechanism to project the sensing beam onto the null space of the communication channel. The hierarchical optimization solution jointly optimizes communication SINR and sensing SCNR, enabling an effective balance between sensing accuracy and communication reliability. Simulation results demonstrate the proposed method’s effectiveness in simultaneously improving sensing accuracy and communication reliability. Full article

While recent advances have successfully integrated neural networks with physical models to derive numerical solutions, there remains a compelling need to obtain exact analytical solutions. The ability to extract closed-form expressions from these models would provide deeper theoretical insights and enhanced predictive capabilities, complementing existing computational techniques. In this paper, we study the nonlinear Gardner equation and the (2+1)-dimensional Zabolotskaya–Khokhlov model, both of which are fundamental nonlinear wave equations with broad applications in various physical contexts. The proposed models have applications in fluid dynamics, describing shallow water waves, internal waves in stratified fluids, and the propagation of nonlinear acoustic beams. This study integrates a modified generalized Riccati equation mapping approach and a novel generalized $\left({\displaystyle \frac{G^{\prime }}{G}}\right)$-expansion method with neural networks for obtaining exact solutions for the suggested nonlinear models. Researchers are currently investigating potential applications of these neural networks to enhance our understanding of complex physical processes and to develop new analytical techniques. The proposed strategies incorporate the solutions of the Riccati problem into neural networks. Neural networks are multi-layer computing approaches including activation and weight functions among neurons in input, hidden, and output layers. Here, the solutions of the Riccati equation are allocated to each neuron in the first hidden layer; thus, new trial functions are established. We evaluate the suggested models, which lead to the construction of exact solutions in different forms, such as kink, dark, bright, singular, and combined solitons, as well as hyperbolic and periodic solutions, in order to verify the mathematical framework of the applied methods. The dynamic properties of certain wave-related solutions have been shown using various three-dimensional, two-dimensional, and contour visualizations. This paper introduces a novel framework for addressing nonlinear partial differential equations, with significant potential applications in various scientific and engineering domains. Full article

This paper explores the application of the generalized beam theory (GBT) in analyzing the buckling behavior of isotropic and composite thin-walled beams with open cross-sections, both with and without branching. The composite beams are composed of orthotropic laminate layers arranged in arbitrary symmetrical orientations. By integrating GBT with the Ritz method and solving the associated generalized eigenvalue problem (GEP), an efficient and robust semi-analytical framework is developed to assess the stability of such isotropic and orthotropic members. The novelty of this work is not the GBT cross-sectional formulation itself, but its implementation at the beam level using a Ritz formulation leading to a generalized eigenvalue problem for the critical buckling loads and mode shapes that capture coupled global, local, and distortional modes in isotropic and orthotropic composite members. This makes the method suitable for early-stage design studies and parametric investigations, where many design variants (geometry, laminate lay-up, and aspect ratios) must be screened quickly without building large-scale high-fidelity finite element (FE) models for each case. The preliminary outcomes, when compared with those obtained using FE, confirm the approach’s effectiveness in evaluating buckling responses, particularly for open-section composite beams. Ultimately, the combined use of GBT and the Ritz method delivers both physical insight and computational efficiency, allowing engineers and researchers to address complex stability issues that were previously difficult to solve. In summary, the methodology can be correctly used for stability assessment of thin-walled composite members prone to interacting global–local–distortional buckling, especially when rapid, mechanistically transparent predictions are required rather than purely numerical FE output. Full article

This study investigates the communication network (MUAVN) of intelligent reflecting surface (IRS)-assisted high-speed multiple unmanned aerial vehicles, considering that highly dynamic UAVs may incur poor performance due to severe channel fading and rapid channel changes. Our objective is to design an adaptive dual-beam tracking scheme that mitigates beam misalignment, enhances the performance of the worst-case UAV, and sustains reliable communication links in the high-speed MUAVNs (HSMUAVNs). We first exploit an attention-based double-layer long short-term memory network to predict the spatial angle information of each UAV, which yields optimal beam coverage that matches to the UAV’s actual flight trajectory. Then, a worst-case UAV’s received beam components signal-to-interference plus noise ratio (SINR) maximization problem is formulated by jointly optimizing ground base station’s beam components and IRS’s phase shift matrix. To address this challenging problem, we decouple the optimization problem into two subproblems, which are then solved by leveraging semi-definite relaxation, the bisection method, and eigenvalue decomposition techniques. Finally, the adaptive dual beams are generated by linearly weighting the obtained beam components, each of which is well-matched to the corresponding moving UAV. Numerical results reveal that the proposed beam tracking scheme not only enhances the worst-case UAV’s performance but also guarantees a sufficient SINR demanded across the entire HSMUAVN. Full article

In bone conduction (BC) hearing, sound is transmitted directly to the cochlea via skull vibrations, bypassing the outer and middle ear. This provides a therapeutic option for patients with conductive or mixed hearing loss and single-sided deafness. Although finite-element models have advanced understanding of the mechanisms underlying BC, progress toward personalized treatment strategies remains limited by a lack of standardized, experimentally validated, subject-specific models. This study proposes a hierarchical validation framework to support the development and validation of individualized computational models of the human head under BC stimulation. The framework spans four anatomical levels: system, subsystems, structures, and tissues. This approach enables systematic acquisition of data from intact cadaver heads down to isolated material domains. To demonstrate the applications of the framework, an experimental study was conducted on a single cadaver head, targeting three levels: the intact head (system), extracted bone pieces (structures), and isolated cortical layers (tissues). Subsystems were not addressed. High-resolution photon-counting computed tomography (CT) and energy-integrating cone-beam CT were used to acquire anatomical data. One-dimensional laser Doppler vibrometry was used to capture vibrational responses of bone pieces and cortical layers under wet and dry conditions. Representative results were analyzed to assess the impact of preparation state on resonance behavior. Comparative analysis showed that photon-counting CT provided superior structural resolution compared with energy-integrating cone-beam CT, particularly at the full-head (system) level. Vibrational measurements at the structure and tissue levels from the same anatomical region revealed broadly consistent resonance vibration patterns, enabling comparison of resonance frequencies. The influence of hydration state and thickness reduction on vibrational behavior was highlighted. The proposed framework provides a scalable methodology for validation of subject-specific BC models with the potential for more accurate BC simulations based on the hypothesis of functional variability rooted in anatomical variability. Obvious use cases would include the development of improved hearing aid designs and personalized treatments. In parallel, a successful correlation of anatomical and functional variability can serve as inspiration for design principles of metamaterials. Full article

The proliferation of wireless sensor networks in industrial Internet of Things (IIoT) applications demands sustainable power solutions that eliminate battery replacement requirements while maintaining operational reliability in varying vibration environments. This paper presents a frequency-tunable magnetoelectric (ME) energy harvester that addresses the fundamental challenge of frequency mismatch between ambient industrial vibrations and harvester resonance through position-dependent magnetic force manipulation. The proposed system employs a Terfenol-D/PMNT/Terfenol-D sandwich transducer mounted on a cantilever beam within an adjustable magnetic circuit, enabling continuous frequency tuning through air gap modification for different magnetic field configurations. A comprehensive theoretical framework incorporating position-dependent magnetic forces was developed to predict the system behavior. Additionally, Multi-walled carbon nanotube (MWCNT)-enhanced epoxy bonding layers with 2 wt.% concentration were analyzed and demonstrated six-fold power improvement over conventional epoxy. The experimental validation shows frequency tuning from 40 Hz to 65 Hz through air gap adjustment of only 1 mm, corresponds to a 62.5% tuning range. Further experimental investigation proves a ten-fold power output improvement up to 2 mW by employing a four-magnet circuit design compared to the two-magnet configuration through specific adjustment of the air gap width. Full article

To meet the strengthening requirements of damaged steel beams in hygrothermal environments, this study conducted four-point bending tests on nine pre-cracked steel beam specimens. The coupled effects of surface roughness, end anchorage, prestressing level of carbon fiber-reinforced polymer (CFRP), and hygrothermal aging on the flexural behavior of the strengthened beams were systematically investigated. Results show that high-grade sandblasting (Sa3) significantly enhances interfacial bond strength through a synergistic “mechanical interlock-adhesion” mechanism, increasing the cracking load of the adhesive layer by 8.2–16.8% compared with Sa2, while partially mitigating the performance degradation caused by hygrothermal aging. The use of end anchorages effectively suppresses CFRP debonding at the beam ends, improving the ultimate load capacity and deformation performance. When a prestress equivalent to 25% of the CFRP’s ultimate tensile strength was applied, the load capacity of the strengthened beams further increased by 10.5–19.3%, interfacial cracking was effectively delayed, and the CFRP utilization efficiency reached 96.8–98.5%. Although hygrothermal exposure accelerated interfacial deterioration and reduced the interfacial cracking load, its influence on the ultimate load was relatively limited. These results offer valuable scientific and engineering insights for the design and interface treatment of CFRP-strengthened steel bridges in hygrothermal regions. Full article

The current study investigates the influence of timber-to-concrete connection types on the behaviour of timber–concrete composite (TCC) structures employing metal web timber joists. Two groups of laboratory specimens were prepared, each comprising four samples with push-joisted beams joined by oriented strand board (OSB) and cast with a concrete layer. One group utilised compliant timber-to-concrete connections via perforated steel tape angles, while the other employed rigid connections through epoxy adhesive and granite chips. The specimens, consisting of two 1390 mm long beams of grade PS10 timber, were tested under three-point bending. Experimental results and finite element analyses demonstrated that specimens with compliant connections exhibited 14–16% greater maximum vertical displacements but only a marginal 1.79% reduction in load-carrying capacity compared to those with rigid connections. Findings indicate that connection compliance markedly affects stiffness and deflection but has a minor impact on ultimate strength. These insights can guide optimisation of TCC members with metal web joists, balancing structural performance and design requirements in sustainable timber construction. Full article

Fiber Bragg Grating (FBG) sensors facilitate compact, multiplexed, and electromagnetic interference-immune monitoring in embedded and harsh environments. The removal of the polymer jacket, a measure taken to withstand elevated temperatures or facilitate integration, exposes the fragile glass. This underscores the necessity of functional coatings, which are critical for enhancing durability, calibrating sensitivity, and improving compatibility with host materials. This review methodically compares coating materials and deposition routes for FBGs, encompassing a range of techniques including top-down physical-vapor deposition (sputtering, thermal/e-beam evaporation, cathodic arc), bottom-up chemical vapor deposition (CVD)/atomic layer deposition (ALD), wet-chemical methods (sensitization/activation, electroless plating (EL), electrodeposition (ED)), fusion-based processes (casting and melt coating), and hybrid stacks (e.g., physical vapor deposition (PVD) seed → electrodeposition; gradient interlayers). The consolidation of surface-preparation best practices and quantitative trends reveals a comprehensive understanding of the interrelationships between coating material/stack, thickness/microstructure, adhesion, and sensitivity across a range of temperatures, extending from approximately 300 K to cryogenic regimes. Practical process windows and design rules are distilled to guide method selection and reliable operation across cryogenic and high-temperature regimes. Full article