Search Results (237)

In this study, a novel aperiodic photonic crystal (PC) structure is designed using the golden ratio-based Lucas sequence, and its infrared (IR) transmission characteristics are investigated. Transmission behavior demonstrates a strong dependence on the number of unit cells and parity (even or odd) of the defect layer repetitions, enabling the formation of a predetermined number of resonant modes around the operating wavelength and broad photonic stopbands at longer wavelengths with sharp defect modes. With its high spectral tunability, the proposed new Lucas sequence-based structure represents a viable candidate for the design of high-performance optical filters and components. These findings indicate that novel Lucas sequence-based PC designs will provide new opportunities for manipulating light–matter interactions in future studies. Full article

Lattice structures offer superior mechanical properties, including lightweight design and performance tailorability, due to their unique geometric configurations and porous characteristics. This study proposes a novel lattice structure, namely the parabolic curved-beam (PCB) lattice structure, in which the struts within the unit cells are designed in a parabolic shape. Based on the principle of minimum potential energy, a theoretical model for the mechanical behavior of the proposed structure under compressive loading was derived. The influence of structural parameters on mechanical performance was systematically analyzed, and the accuracy and validity of the theoretical model were verified through experimental design. Additionally, the advantages of the structure were explored through comparison with the traditional body-centered cubic (BCC) lattice structure. Subsequently a response surface surrogate model was constructed using orthogonal experimental design, yielding quadratic regression equations for key mechanical indicators, including Young’s modulus, specific energy absorption (SEA), and yield strength. The results demonstrate that optimal mechanical performance is achieved with a strut curvature of 0.55 mm⁻¹, a cross-sectional area of 1.22 mm², and a unit cell size of 5 mm. Under these design parameters, the structure exhibits a Young’s modulus of 4152.85 MPa, an SEA of 3.86 J/g, and a yield strength of 17.02 MPa. The findings demonstrate that the present study employs theoretical analysis and optimization design to achieve mechanical characterization and performance optimization of the designed lattice structure. It shows broad application prospects in fields such as aerospace, vehicle engineering, and protective equipment, where there is an urgent demand for lightweight and high-strength materials. This work provides new insights and a theoretical basis for the design and performance optimization of multi-functional integrated structures in engineering practice. Full article

This work proposes a polarization-insensitive scalable wide-angle metasurface array for highly efficient ambient energy harvesting in the 5.8 GHz Wi-Fi band. Inspired by dipole antenna principles, we design an asymmetric planar orthogonal dipole-based metasurface featuring monolithic integration of Schottky diodes (HSMS-2860) at unit cell feed gaps. This novel direct-impedance-matching strategy eliminates conventional matching networks, reducing energy conversion losses while enabling 99% radiation-to-AC efficiency across all polarization angles at 5.8 GHz. The coplanar architecture interconnects metasurface unit cells via inductors, simultaneously establishing low-loss DC channels and suppressing RF leakage. Fabricated as a 5 × 5 array, the prototype achieves 77.9% peak RF-to-DC efficiency with polarization insensitivity at an incident power of 25 dBm. Furthermore, with incident powers of 15 dBm and 20 dBm, the proposed metasurface array attained RF-to-DC conversion efficiencies exceeding 40% and 60%, respectively. This result indicates that the array is capable of achieving high energy harvesting efficiency across a broad power range. This scalable, drill-free, and polarization-insensitive design demonstrates strong potential for harvesting ambient RF energy in real-world multipath environments. Full article

Capacitive micromechanical ultrasonic transducers (CMUTs), as microelectromechanical systems (MEMS) devices, have broad application prospects in ultrasonic imaging and sensing. This study investigates the influence of surface acoustic waves (SAWs) using periodically arranged CMUTs as the fundamental unit cells. We first utilize finite element analysis (FEA) to calculate and analyze the band structure and bandgap characteristics of phononic crystals under infinite periodic conditions. Subsequently, for finite periodic structures in practical applications, acoustic transmission spectra were further simulated using FEA to verify the bandgap characteristics of the structure for SAWs. Accordingly, this paper leverages a deep learning framework based on a multilayer perceptron (MLP) architecture to achieve the inverse design and optimization of CMUT geometric parameters, tailored to specific target bandgap requirements. The results demonstrate that this approach can efficiently and accurately determine the optimal structural configurations, offering a robust and novel technical paradigm for the precise control of SAWs using CMUT-based periodic arrays. Full article

In this paper, a multi-feed transmitarray with high-gain, wide-angle beam-scanning, and low-cost features is presented. A novel hybrid phase distribution (HPD) method is proposed to improve the beam-scanning range by combining the single-focal and bifocal principles according to the actual feed illumination area. By using the proposed method, the phase distribution of the transmitarray for different scanning angles can be obtained more accurately, thereby reducing the phase error between the actual and ideal phase distributions. To construct the transmitarray, a three-layer polarization conversion unit cell, consisting of two orthogonal polarizers in the outermost layers and a polarization rotating patch in the middle layer, is designed to provide high-efficiency transmission and full 360° phase coverage. Based on the HPD method, a single-polarized transmitarray antenna with a focal diameter ratio of 0.28 is designed and simulated. The simulated results show that the enhancement of the beam-scanning range is successfully realized. This design can perform a discrete ±60° beam-scanning range with a peak gain of 24 dBi. The gain losses of 0.7 dB at ±30° and 4.7 dB at ±60° are achieved. The cross-polarization levels are about 44 dB and 35 dB at 0° and −60° scanning angles, indicating low cross-polarization of the proposed solution. A five-beam prototype is fabricated and measured for experimental verification purposes. The measured results demonstrate good consistency with the simulations in the main lobe, with slight deviations due to practical fabrication and measurement constraints. The proposed design has advantages such as low-cost, wide beam-scanning angle, high-gain, low-profile and easy fabrication. Full article

Enhancing the robustness and fault tolerance of finite-state machines (FSMs) is crucial for safety-critical systems, such as transportation control systems and medical equipment. This issue becomes particularly important when developing control units for unmanned aerial vehicles (UAVs), which are exposed to external disturbances from electronic warfare (EW) systems. Under such conditions, traditional methods for creating fault-tolerant finite-state machines (FTFSMs), initially designed to address the effects of ionizing radiation that cause rare single-event upsets (SEUs), are often ineffective. This paper proposes a novel method for developing FTFSMs that can withstand multi-bit upsets (MBUs) affecting the FSM’s wires and memory cells due to external disturbances. The FTFSM architecture additionally includes an output register and a concurrent error detection (CED) circuit. When a fault is detected, the FTFSM switches to standby mode. Once the external disturbance ceases, the FTFSM resumes normal operation from the point of interruption without altering the control algorithm. In cases of critical errors, the FSM circuit can be reconfigured via the system processor. Experimental studies have shown that the proposed approach incurs exceptionally low overhead costs. Additionally, the paper presents a technique for calculating the probability of fault detection for FTFSMs implemented in field-programmable gate arrays (FPGAs). Full article

To address the limitations of conventional metamaterials in thermo-mechanical coupling environments, this study proposes a multifunctional metamaterial structure through material selection and structural optimization, demonstrating stable vibration isolation performance under thermal fluctuations. The thermal deformation mechanisms and zero thermal expansion (ZTE) behavior of curved-beam unit cell are systematically examined through the chained beam constraint model (CBCM). A novel dual-zero metamaterial featuring both quasi-zero-stiffness (QZS) and ZTE characteristics is developed using curved-beam unit cell design. A parametric analysis, through finite element modeling, systematically investigated the effects of geometric parameters and material properties on the thermal expansion deformation and mechanical responses in the curved-beam unit cell structure. Furthermore, cylindrical metamaterials featuring dual-zero properties were engineered, and their deformation control mechanisms and vibration characteristic evolution across a broad temperature range were systematically studied. The simulation results indicate that while the Al–Al structure exhibits a significant resonance peak shift of up to 64.32% at 200 °C, the Al–Steel zero-stiffness design restricts this shift to only 7.72%. Furthermore, the Steel–Invar configuration demonstrates exceptional vibrational stability, with its center frequency shifting marginally from 5.58 Hz to 5.61 Hz at 200 °C. This methodology presents a viable solution for engineering metamaterials in extreme-temperature environments. Full article

This study proposes a novel parameterized hollow spiral lattice (HSL) structure designed for additive manufacturing (AM). The structure is composed of two right-handed and two left-handed spiral members. Its unit cell is formed by sweeping a circular ring cross-section along a cylindrical helical path, creating a porous topology that integrates continuous flow channels with structural load-bearing capability. An analytical model correlating key design parameters, including spiral radius, helix angle, and tube inner/outer diameters, with the structural relative density is established. Considering the manufacturability constraints of Laser Powder Bed Fusion (LPBF), an adaptive parametric design framework is developed to simultaneously optimize the geometry, relative density, and process feasibility. Ti6Al4V HSL samples were fabricated using LPBF. Their thermo–mechanical performance was systematically characterized through Computational Fluid Dynamics (CFD) simulations, Finite Element Analysis (FEA), and quasi-static compression experiments. Thermal analysis under internal and internal–external flow conditions reveals that the centrifugal force induced by the spiral geometry generates Dean vortices. This enhances momentum exchange between the central mainstream and near-wall fluid, significantly improving radial mixing, promoting temperature uniformity, and effectively suppressing local hot spots. Mechanically, the HSL exhibits significantly superior specific strength and stiffness compared to traditional body-centered cubic (BCC) and diamond lattices, approaching the performance of cubic topology, thus demonstrating outstanding lightweight load-bearing potential. The developed HSL structure presents a promising innovative design strategy for next-generation applications requiring integrated thermal management and structural load-bearing functions. Full article

This study develops a novel Locally Rib-Reinforced Rotational Hexagonal Honeycomb (LRRH) model. The objective is to systematically enhance the model’s mechanical performance and energy absorption efficiency through geometric morphology construction. The structure combines triangular and hexagonal units through a rotational arrangement, forming a rotating rigid structure (RRH), upon which re-entrant parallelogram units are embedded. A Finite Element simulation was developed in Abaqus/Explicit. Its reliability was validated by comparing the numerical predictions against the outcomes of quasi-static compression experiments. The axial impact response and energy absorption attributes of the configuration were thoroughly evaluated by adjusting the hexagonal cell angles and applying a symmetric design approach. The experimental outcomes indicate that the SEA of the RRH-Type I-180°-180° model surpasses that of the RRH-Type I-105°-105° by 43.68%, and the SEA of the LRRH-Type I-105°-105° achieved a significant 97.88% increase compared to the LRRH-Type I-180°-180° variant. Meanwhile, the SEA of the RRH-Type I-180°-180° honeycomb increased by 121.2% and 11.79% compared with the LRRH-Type I-180°-180° and LRRH-Type I-105°-105° structures. Parametric analysis results indicate that wall thickness and impact velocity are critical factors influencing energy absorption performance. The enhancement of structural thickness considerably strengthens its flexural resistance and pressure tolerance. Full article

An efficient deep-learning-based framework for optimization-based inverse design of electromagnetic metasurface design is proposed in this paper. A novel unit-cell parameterization strategy generates 16-element structures via symmetry operations governed by ten geometric parameters, overcoming the inefficiencies of pixel-based representations. A dataset of 16,000 parameter–reflection phase pairs is constructed, and a hybrid model combining Convolutional Neural Network (CNN), attention mechanisms, and the Kolmogorov–Arnold Network (KAN) is developed for broadband response prediction. The coefficient of determination (R²) of the proposed model is 0.8837 in the 2–18 GHz band, which is 44.87% higher than the R² without KAN. The proposed chessboard metasurface achieves a 10 dB monostatic radar cross-section (RCS) reduction under normal incidence over a wide frequency band from 7.4 to 15.2 GHz, corresponding to a relative bandwidth of 69%. This approach provides a generalizable, data-efficient solution for intelligent metasurface design. Full article

Previous studies on reconfigurable intelligent metasurface (RIS) design have primarily relied on full-wave electromagnetic simulation software, which often incurs high computational costs and lacks clear design direction. The design of multi-bit RIS remains challenging and there is currently no suitable systematic method for selecting the corresponding tuning devices. To overcome these limitations, this article proposes a novel equivalent circuit-based approach to RIS design. In contrast to the conventional approach, where the equivalent circuit model is derived from post-design evaluation of the scattering properties of RIS, our work is entirely driven by the equivalent circuit model from the outset to accomplish the unit cell design. A complete workflow as well as details of each constituent step are presented for the topology design of RIS based on equivalent circuit topology. Building on this circuit topology, a 3-bit reflective phase reconfigurable unit cell is developed based on a tunable band-stop filter circuit. We conducted adjustable phase verification experiments and beam deflection experiments. The consistency between the experimental results and circuit theory demonstrates the feasibility and practicality of the equivalent circuit method of RIS design. This circuit-to-structure methodology provides a physically interpretable and systematic framework for designing RIS with arbitrary electromagnetic responses, offering new insights into RIS design. Full article

Background: Recent advancements in regenerative medicine have introduced mesenchymal stem cell–derived exosomes (MSC-Exos) as a novel therapeutic approach. Exosomes are extracellular vesicles containing proteins, lipids, and RNAs capable of modulating cellular behavior and promoting tissue regeneration. A systematic review of human studies is warranted to summarize outcomes, assess therapeutic value, and guide clinical applications. Objectives: This systematic review synthesizes current evidence on mesenchymal stem cell–derived exosomes for cutaneous scars, aging, and hyperpigmentation, with a focus on functional and aesthetic outcomes. Method: A comprehensive search of PubMed, Scopus, Embase, Web of Science, and Google Scholar (January 2010–July 2025) was performed following 2020 PRISMA guidelines. Eligible studies included studies that were randomized controlled trials, pilot studies, case series, and case reports involving human participants treated with MSC-Exos. Outcomes assessed were scar remodeling, pigmentation, skin regeneration, recurrence, and adverse events. Data extraction and bias assessment were conducted independently. Result: Six studies (n = 99; age 19–72 years) from diverse regions, including the United States, the Republic of Korea, and México, were included. MSC-Exos therapy showed promising improvements in reducing scar thickness (32.5% vs. 19.9%, p < 0.01), wrinkle parameters were reduced by 1 (2.4–14.4% vs. 6.6–7.1%, p < 0.05), and elasticity was enhanced (+11.3% vs. −3.3%, p = 0.002) Additional benefits included hydration (+6.5% vs. +4.5%, p = 0.37) and reduced melanin index (−9.9% vs. −1%, p = 0.44). The Global Aesthetic Improvement Scale score showed significant improvement (p = 0.005). Using the Investigator Global Assessment, 16 out of 25 areas treated with exosomes showed significant improvement (grade ≥ 2), compared to 12 out of 25 areas in the control group (p = 0.02), indicating that exosome treatment led to more visible improvement. Complete resolution of icepick scars, partial improvement of boxcar/rolling scars, and no recurrence of keloids (18/21) were reported. Adverse events were mild and transient. Conclusions: Early human evidence suggests that MSC-Exos may offer potential therapeutic benefits for scars, hyperpigmentation, and skin aging, with favorable short-term safety profiles. However, the current evidence remains preliminary due to small sample sizes, heterogeneous study designs, and limited follow-up durations. Larger, well-designed randomized trials are needed to confirm long-term efficacy and safety. Full article

This study details the design, synthesis, and evaluation of a novel series of fourteen 2-((1H-1,2,4-triazol-5-yl)thio)-N-benzylidene-N-arylacetohydrazide hybrid compounds. The primary objective was to investigate their potential as antimicrobial agents and assess their cytotoxicity. A systematic approach combining in silico screening and experimental validation was employed. The initial in silico analysis, using SwissADME, identified compounds with favorable drug-like properties. Subsequently, all fourteen compounds were synthesized and characterized using various spectroscopic methods. Their antibacterial efficacy was evaluated in vitro against Gram-negative (Klebsiella aerogenes) and Gram-positive (Enterococcus sp.) bacteria through growth kinetics and colony-forming unit (CFU) assays. Cytotoxicity was assessed using MTT assays on HEK (human embryonic kidney) cell lines. The compound, 2-((1H-1,2,4-triazol-3-yl)thio)-N′-(2-fluorobenzylidene)-N-phenylacetohydrazide emerged as the most promising candidate, demonstrating broad-spectrum antibacterial activity. These findings highlight the potential of 2-((1H-1,2,4-triazol-5-yl)thio)-N-benzylidene-N-arylacetohydrazide hybrids as a scaffold for developing new antimicrobial agents. Furthermore, this study suggests possible environmental applications for these compounds in antimicrobial resistance (AMR) management. Full article

This paper presents a 3-bit transmissive intelligent surface (TIS) using a novel technique that employs a unit cell comprising loaded semi-loop dipole resonators. The two resonators are anti-symmetrically oriented along the H-plane, functioning as transmitter and receiver on opposite sides of the TIS. The unit cell, with 13.2 mm periodicity, achieves 360° phase variation in 45° steps while maintaining insertion loss below 2 dB at 10 GHz. A 17 × 17 array TIS is designed using ray tracing and phase shift compensation techniques, with phase profiles distributed across eight discrete varactor states. The implemented TIS demonstrates a 10.8 dB gain enhancement for a horn antenna source at 10 GHz while preserving antenna matching, polarization, and radiation efficiency. The design achieves beam steering capabilities up to 60° with ±2° precision across elevation, azimuth, and inclined angles, maintaining an average steering gain loss of 3 dB over a 400 MHz bandwidth. These characteristics make the proposed design particularly effective for modern wireless coverage extension and tracking applications. Full article

Cultured meat has progressed from early in vitro cell culture concepts to regulatory approvals and preliminary commercialization, with recent advancements propelled by interdisciplinary innovations in cell line engineering, serum-free media, bioreactor design, and three-dimensional (3D) assembly technologies. This review synthesizes recent developments from 2023 to 2025, utilizing peer-reviewed publications, patent analyses, regulatory frameworks, and media reports to assess global preparedness for large-scale production. Asia has emerged as a leading hub, with China, Japan, South Korea, and Singapore focusing on scaffold-based 3D cultures, bioinks, and serum-free strategies, complemented by national centers and pilot facilities. The United States leverages its technological advancements and established regulatory framework, as evidenced by recent Food and Drug Administration and United States Department of Agriculture approvals. However, potential complications related to political regional bans and legislation may arise. Europe and the UK prioritize defined media, cell optimization, and structured novel-food regulations, with early commercialization primarily in pet food. Looking ahead, the industrialization of cultured meat is anticipated to be driven by process engineering and hybrid product strategies, with initial pilot-to-demonstration facilities established in countries open to alternative food products. Premium and hybrid cultured meat products are expected to enter the market first, while whole-cut cultured meat is likely to remain a premium offering into the early 2030s. Full article