In this study, a dual-band active antenna integrated with an IoT healthcare monitoring system for measuring body temperature, heart rate, and SpO₂ is presented. A MAX30100 sensor and NodeMCU ESP32-CAM enable data acquisition and cloud-based monitoring through Ubidots. The antenna, fabricated on a Rogers Duroid RO3003^TM substrate (37 × 42 × 1.52 mm³), operates at 2.4 GHz and 5.8 GHz using an inverted U-shaped slot and a PIN diode for frequency reconfiguration. Received Signal Strength Indicator (RSSI) measurements showed improved signal strength from -35 to -40 dBm compared to -40 to -45 dBm for the on-board antenna. Experimental evaluation on three volunteers aged 21, 36, and 55 years demonstrated reliable physiological monitoring, with heart rate values of 84-90 BPM and temperature readings of 30-36°C. The results validate the suitability of the proposed antenna for reliable IoT-based healthcare applications.

In this paper, a compact ultra-wideband (UWB) bandpass filter (BPF) with triple-notch bands (TNBs) is proposed and demonstrated. We present a cross-shaped anti-shorted coupled-line structure employing a single coupled multi-mode resonator (MMR), whose resonant characteristics and intrinsic transmission zeros are investigated by employing the even-odd mode analysis method. In addition, the three notch bands are generated from the resonator's intrinsic transmission zeros without requiring any additional notch circuits. At the same time, their center frequencies can be quasi-independently controlled by properly adjusting the microstrip electrical lengths. For demonstration, the proposed filter is designed, fabricated, and measured. Simulated and measured results are in good agreement. The measured results agree well with theoretical predictions, which exhibit superior performance, such as triple-notch bands, high skirt selectivity, an ultra-wide passband from 2.8 to 12.5 GHz with a fractional bandwidth of 138%, a compact size of only 7.7 mm × 9.2 mm, and effective notched-band suppression levels.

To address the challenges of coordinating local reactive power compensation with cross-station harmonic interaction suppression in hybrid multi-infeed HVDC (HMIDC) systems, this study proposes an optimal AC filter configuration method based on sensitivity analysis. A harmonic impedance equivalent model was established for a hybrid three-infeed HVDC system, and a comprehensive harmonic interaction index was constructed based on harmonic current interaction influence coefficients. Normalized sensitivity analysis was then performed on the AC filter impedance, receiving-end AC system impedance, and tie-line impedance at the 11th and 13th harmonics. The results indicate that the AC filter impedance serves as the dominant adjustable factor. On this basis, a discrete optimization model was developed, with the number of DT11/24 and DT13/36 double-tuned filter groups in service as decision variables. In addition, this model considers equipment limits, minimum filtering requirements, reactive power compensation, and harmonic voltage constraints. Case study results show that the optimized configuration reduces the overall harmonic coupling among HVDC infeed systems; in particular, the interaction strength from the second conventional HVDC link to the modular multilevel converter-based high-voltage direct current (MMC-HVDC) link at the 13th harmonic decreases by approximately 32%. The proposed method provides a practical reference for coordinated AC filter switching in HMIDC.

This study introduces a compact, low-profile ultra-wideband (UWB) wearable antenna designed for wireless body area network (WBAN) applications. The antenna incorporates a rectangular patch on a flexible jeans substrate, incorporating one patch slot, four identical edge slots, and a defected ground structure (DGS) with a compact dimensions of 23 mm × 30 mm × 1.5 mm. These slots and DGS enable the UWB operation with an excellent bandwidth while maintaining a good balance among the key performance parameters such as efficiency, gain, and SAR, which is the main contribution of this study. The antenna performance was analyzed using a four-layer human body phantom model that includes skin, fat, muscle, and bone layers. It operates across the frequency range of 2.82-11.25 GHz, covering the UWB range for wearable devices, and achieves a peak gain of 3.79 dBi, an average gain of 2.36 dBi, a peak efficiency of 63.36%, and an average efficiency of 52.88%. In addition, the obtained SAR values are 0.549 W/kg and 0.391 W/kg at 5 GHz, and 0.0727 W/kg and 1.97 W/kg at 9 GHz for 1 g and 10 g tissue standards, respectively, complying with SAR regulatory standards. Moreover, bending analysis validated its stable performance under various angles and deformation conditions. The fabrication and on-body testing of the proposed antenna exhibited a bandwidth of 1.38-12 GHz, demonstrating compliance with simulations. Finally, a human body temperature monitoring prototype was developed, which validates its suitability for wearable WBAN applications.

To realize a compact and low-profile Ka-band SIW antenna with continuous wideband operation, a wideband SIW slot antenna based on split Magnetic-electric dipole multi-mode coupling is proposed. The central design idea is to transfer electromagnetic energy from the lower SIW cavity to the upper radiating layer through aperture coupling and to merge two adjacent resonant modes generated by the electric- and magnetic-dipole components. The antenna employs a dual-layer configuration. The lower layer consists of an SIW feeding cavity and a coupling slot, and the upper layer incorporates split arc-shaped patches, a central coupling patch, metallized vias, and a cross-shaped perturbation structure. The split patches mainly generate the high-frequency electric-dipole mode, while the central coupling patch and metallized vias introduce an adjacent lower-frequency magnetic-dipole mode. The cross-shaped perturbation structure further optimizes the impedance transition between the two modes. The simulated results show that the antenna achieves an impedance bandwidth of 26.35-29.20 GHz for |S₁₁| < -10 dB and a peak realized gain of approximately 8.15 dBi at 28 GHz. The fabricated prototype exhibits a measured impedance bandwidth of approximately 26.8-29.1 GHz. In addition, the simulated multifrequency radiation patterns and efficiency results demonstrate relatively stable broadside radiation characteristics within the operating band. The proposed antenna provides a compact and readily integrated solution for Ka-band millimeter-wave communication systems.

A novel finite-gap lumped-port model is presented to improve the accuracy of the volume surface integral equation (VSIE) solver for electromagnetic (EM) radiation from composite metallic-dielectric structures. This port model is implemented by modifying the traditional method of moments (MoM) solution to use a novel divergence-conforming testing function at the gap as well as half-basis functions connected across the gap, where a small gap region in the domain of analysis is linked to the lumped-circuit voltage/current source. Then, a hybrid multilevel fast multipole algorithm with multilevel accelerated Cartesian expansion algorithm (MLFMA-MLACEA) is adopted to enhance the capability of this VSIE-based finite-gap lumped-port model for electrically large and multi-scale EM radiation problems. Numerical results are provided to demonstrate the accuracy and efficiency of this VSIE method.

To address the problems of low speed control accuracy and performance degradation caused by time-varying disturbances in conventional control methods for high-precision speed regulation of permanent magnet synchronous motors (PMSMs), an improved full-order model-free sliding mode control (IFOMFSMC) method based on full-order sliding mode control (FOSMC) is proposed. First, a novel ultra-local model under parameter perturbations is established. Based on this model, the IFOMFSMC is designed by combining a second-order full-order sliding mode surface with an improved double-power reaching law, which improves the speed control accuracy of the PMSM. Subsequently, a full-order extended sliding mode disturbance observer (FOESMDO) is developed by incorporating FOSMC into the extended disturbance observer. The FOESMDO estimates unknown disturbances more accurately, thereby compensating the IFOMFSMC and enhancing system robustness under complex time-varying disturbances. Finally, simulation results confirm accurate speed tracking with the proposed method. Under complex time-varying disturbance conditions, compared with the conventional control method, the IFOMFSMC improves speed response and tracking performance by 57.6% and 88.2%, respectively, while reducing steady-state speed error and torque ripple by 71.8% and 29.2%. The proposed method effectively enhances steady-state and dynamic performance as well as disturbance-rejection capability.

The open-circuit fault diagnosis of switches in quasi-Z-source inverters (qZSI) is challenging. Existing methods struggle to simultaneously achieve high robustness and low computational complexity without additional sensors. In this study, an open-circuit fault diagnosis method based on an improved super-twisting non-singular fast terminal sliding-mode observer (IST-NFTSMO) and hybrid features is proposed. The stator currents were estimated in real time by the IST-NFTSMO, and residuals were generated accordingly. By analyzing differences in the statistical distributions of residuals between healthy and faulty conditions, two features were extracted: average log-likelihood ratio (ALLR) and signed cumulative ratio (SCR). The ALLR is used for rapid fault detection, whereas the SCR is used for accurate localization of faulty switches. The proposed method was implemented entirely based on existing current sensors. No additional voltage sensors were required. Moreover, the diagnostic thresholds are adaptively adjusted according to variations in speed and load. The experimental results demonstrate that both single-switch and dual-switch open-circuit faults can be diagnosed rapidly and accurately. Compared with conventional methods, higher robustness and lower computational complexity were achieved.

This paper presents the design, fabrication, and characterization of a novel optical fiber temperature sensor based on a single-mode-multimode-single-mode (SMS) structure for real-time monitoring of transformer oil temperature in high-voltage environments, addressing the limitations of conventional electronic sensors such as electromagnetic interference, electrical safety hazards, and restricted spatial coverage. The sensor, fabricated with corning single mode fiber (SMF)-28e+ single-mode and Thorlabs FG050UGA multimode fibers (5 cm active section), operates on the Mach-Zehnder interferometer principle, where temperature-induced refractive index changes in transformer oil modulate light propagation. Systematic experiments over a 30-90 °C range using a 1550 nm tunable laser, temperature‑controlled oil bath, Pt100 reference, and optical spectrum analyzer yielded a wavelength sensitivity of 4.17 × 10^-3 nm/°C with excellent linearity (R² = 0.9646), a standard error of 4.45 °C, repeatability better than 0.5 % coefficient of variation, and progressive OSNR improvement from 0 dBm at 30°C to 2.26 dBm at 90 °C. The wavelength-based calibration method significantly outperformed the power-based approach, offering 1.36× lower error (4.45 °C vs. 6.04 °C) and higher correlation, with expanded uncertainty (95 % confidence, k = 2) calculated as 6.14°C. Compared to fiber Bragg grating and fiber-loop mirror sensors, the proposed SMS sensor provides electromagnetic immunity, cost-effective fabrication, high stability, and a simple all-fiber configuration, making it a reliable and practical solution for continuous thermal monitoring in power transformers and laying the foundation for comprehensive fiber-optic sensing networks in high-voltage power systems.

To address vibration and noise issues in outer-rotor flux-switching permanent-magnet (OR-FSPM) machines for high-precision applications, radially magnetized PMs are placed between regular tangentially magnetized PMs, forming a U-shaped structure. An air-gap magnetic barrier is introduced between the two types of PMs to achieve magnetic isolation. Then, the spatiotemporal distribution of radial electromagnetic force density (EFD) waves is derived based on the magnetomotive force permeance model. Modal and harmonic response analyses are then conducted for both the conventional and proposed U-shaped machine topologies using electromagnetic-structural field simulations to reveal vibrational characteristics. The results demonstrate that the proposed U-shaped topology effectively suppresses second-order resonance while maintaining superior electromagnetic performance.

In fixed switching frequency pulse-width modulation (PWM) drive systems for switched reluctance motors (SRMs), the duty cycle directly affects current-tracking precision and torque output performance. To address the slow dynamic response of conventional PI control and the model dependence and limited robustness of conventional model predictive duty-cycle control (MPDCC), this study proposes a robust duty-cycle control strategy based on double-power sliding mode compensation. This strategy constructs a duty-cycle generation mechanism by combining model predictive feedforward with sliding-mode compensation. It utilizes MPDCC to generate a base duty cycle, whereas a double-power sliding mode generates a compensation duty cycle to correct deviations. Simulated and experimental results demonstrate that the proposed strategy generates accurate PWM duty cycles, keeps the current tracking error bounded within a small quasi-sliding-mode band, and improves current-tracking accuracy and torque-ripple suppression under parameter-mismatch conditions, validating the robustness of the system against parameter mismatches.

The design of ultra-wideband (UWB) band-notched antennas is highly sensitive to geometric dimensions. Consequently, traditional metaheuristic algorithms incur prohibitive computational costs from massive full-wave electromagnetic (EM) simulations. An efficient co-design framework, termed the Surrogate-Assisted Nutcracker Optimization Algorithm with Gaussian Process (SANOA-GP), is proposed. By leveraging a GP surrogate for epistemic uncertainty quantification with a lower confidence bound (LCB) prescreening strategy, SANOA-GP balances exploration and exploitation, overcoming high-dimensional multimodal traps. Moreover, intelligent early stopping is achieved through a performance-driven dual-termination criterion with a progressive reward mechanism. Sobol global sensitivity analysis is incorporated to quantitatively evaluate geometric influences, enhancing black-box interpretability and verifying the independent tunability of the dual notches. Measurement results confirm that the optimized antenna achieves precise and deep notches (S₁₁ > -5 dB) at the 5G N79 and X-band frequencies. Remarkably, SANOA-GP converges with an average of only 69.3 full-wave EM simulations. Compared to surrogate-free algorithms, it reduces computational time by over 50%, while still ensuring high optimization accuracy and physical reliability. The proposed framework offers an efficient and reliable paradigm for the automated design of complex radio frequency (RF) and microwave components.

The conventional optimization of permanent magnet synchronous motors (PMSMs) for hybrid electric vehicles (HEVs) often neglects the dynamic nature of real-world driving cycles, resulting in suboptimal overall energy efficiency. To address this issue, this study proposes a multi-region efficiency optimization strategy that fully integrates actual driving cycles. First, motor operating points were extracted from the WLTC and CLTC standard driving cycles and identified as key operating regions via cluster analysis. A variance-based sensitivity analysis is then employed to quantify the contribution of each rotor parameter, thereby reducing the optimization dimension. The NSGA-III algorithm, coupled with finite element analysis (FEA), performs multi-objective optimization, targeting average efficiency and permanent magnet cost. A new method that comprehensively considers the average efficiency of both the cluster centers and boundaries of the operating points was proposed as an optimization objective. The results show that the optimal candidate improves the average efficiency to 96.77\%. Depending on the practical requirements, different candidate points are ultimately selected by balancing efficiency, cost, and driving comfort.

Accurate prediction of magnetic forces in air-core coil systems is essential for the design and optimization. Accurate magnetic-force prediction in air-core coil systems is essential for electromagnetic actuators, wireless power transfer, inductive coupling, magnetic calibration, and coil-based positioning systems. This paper presents a software-validated computational framework for predicting axial and radial magnetic forces in practical air-core coil systems under aligned and misaligned conditions. The framework extends ideal coaxial coil-force analysis by including lateral offset, angular tilt, finite coil dimensions, discrete winding geometry, helical winding pitch, finite conductor diameter, and nonuniform conductor placement. Three complementary physics-based methods are implemented and compared: a semi-analytical elliptic-integral method for rapid coaxial and near-coaxial evaluation, a direct numerical-integration method based on the Lorentz-force interaction integral, and a filament-based discrete-winding method for practical conductor geometry. Independent Ansys Maxwell simulations are used as the finite-element software-validation reference under identical geometric and electrical conditions. This work is limited to software-based validation; physical experimental validation using real coil pairs is identified as future work. The validation results show strong agreement among the proposed methods and Ansys Maxwell simulations. The final software mesh-independence change is 0.15%, the boundary-domain sensitivity is 0.12%, and the maximum relative half-spread among the physics-based methods is 0.55%. The maximum axial-force deviation in the coaxial separation sweep is 0.62%, and the radial-force sign-symmetry error remains below 0.23%. Including practical winding details reduces the model-to-software vector error from 2.87% for the continuous-current approximation to 0.10% for the full practical winding model. A feedforward neural-network surrogate model trained using 12,000 validated samples is also introduced for rapid interpolation within the sampled design domain. The surrogate achieves R²=0.996-0.998, mean relative error below 1.20%, and maximum relative error of 5.00% on unseen test data. The proposed framework provides an accurate, efficient, and physically interpretable tool for axial and radial force prediction in practical misaligned air-core coil systems.

Halide perovskites have demonstrated both short-term and long-term synaptic plasticity behaviors through various physical mechanisms, making them suitable neuromorphic electronics. However, most studies rely on distinct materials or device architectures optimized for one single mechanism, limiting the realization of both forms of synaptic plasticity within a unified material system. Here, we report ionic-ferroelectric halide perovskite (IFHP) artificial synapses that integrate two fundamentally different resistance switching processes within a single material. This functionality is enabled by the ferroelectric Dion-Jacobson perovskite (4-AMP)PbI₄ (4-AMP = 4-(aminomethyl)piperidinium), which exhibits ion-migration-dominated behavior below the coercive voltage (V_C ~ 3.5 V) and ferroelectric polarization switching above. Accordingly, the device exhibits volatile paired-pulse facilitation without stable non-volatile memory retention under sub-coercive stimulation, while exhibiting increasing non-volatile memory above V_C. The ferroelectric-polarization-driven long-term plasticity is further supported by extended retention over 2 × 10⁴ s, cycling operation, and device-to-device reproducibility. In addition, the IFHP artificial synapse emulates bio-inspired associative learning and nociceptive sensory functions, highlighting its potential as neuromorphic hardware. These results establish a single-material pathway for voltage-programmable mixed plasticity, addressing a key challenge in halide perovskite neuromorphic hardware.

To improve beam collection efficiency (BCE) while suppressing sidelobes and limiting implementation complexity in microwave wireless power transmission (MWPT) transmitting arrays with a small number of subarrays, this paper proposes an axially symmetric sparse planar array (SDASPA) model and a one-step subarray-division algorithm named RT-DWCFPSO-SD. The proposed model exploits axial symmetry to reduce search dimension and facilitate a simplified feeding structure. The proposed algorithm jointly optimizes element positions, element excitations, and subarray boundary parameters by combining a constriction factor, dynamic inertia weight, and ring topology. Numerical simulations on an 8 × 8 array with an aperture of 4.5λ × 4.5λ show that, when the array is divided into three subarrays, the proposed method achieves a BCE of 93.42% and a CSL of -13.19 dB. These results indicate that the proposed method is a promising design tool for MWPT transmitting arrays under limited subarray-division conditions.

Reconfigurable Intelligent Surfaces (RIS) have become a trend recently and represent a revolutionary development in wireless communications. Although RIS is utilized to enhance spectrum efficiency, particularly in Multi-User Multi Input Multi Output (MU-MIMO) environments, the conventional diagonal RIS(D-RIS) architecture represents a significant limitation. Beyond-diagonal RIS designs, such as fully-connected (FC-BD-RIS) and group-connected (GC-BD-RIS), are effective in controlling scattering and performance due to their use of reflective RIS elements. This research analyzes in detail the simulation of FC-BD-RIS, GC-BD-RIS, D-RIS and baseline NO-RIS architectures assuming a real communication environment. The results show that the FC-BD-RIS architecture achieves the best performance and highest rate under all operational conditions, while the GC-BD-RIS architecture showed balanced and efficient performance relative to the computational complexity compared to the FC-BD-RIS. Ultimately, the behavior of per-user rate has demonstrated the ability of beyond-diagonal BD-RIS architectures to suppress interference and achieve fairness within MU-MIMO scenarios. Based on the results of this work, GC-BD-RIS is the most practical and suitable for future large-scale 6G applications. This work draws attention to the trade-off among design, optimization, and achievement of RIS-enabled MU-MIMO systems.

Objective: This study aims to experimentally and numerically investigate the modulation of electromagnetic wave physical characteristics (transmittance, absorptance, impedance) by strongly an isotropic acoustic materialism in the 2-12 GHz frequency band, and to quantify the influence of material parameters (thickness, density, elastic modulus, an isotropic direction) on wave control performance. Methods: Three types of material units (metal composite, polymer, ceramic reinforced) with thicknesses of 1.5-3 mm and anisotropic directions along X, Y, Z axes were fabricated. Transmittance and absorbance were measured using a vector network analyzer with a WR-90 guideway system. Finite element simulations incorporating acoustic-electromagnetic coupling (strain-induced permittivity modulation) were conducted. Sensitivity analysis was performed by varying thickness (±10%), elastic modulus (±5 GPa), density (±500 kg/m³), and direction angle (±15°). Results: High-frequency absorbance reached 0.91 (metal composite at 9.5 GHz), while low-frequency transmittance remained above 0.70. Thickness and elastic modulus predominantly affected the amplitude and position of high-frequency absorption peaks, whereas density and direction angle primarily regulated low-frequency response, resulting in multi-peak broadband absorption. The deviation between experimental data and finite element simulation was less than 3%. Sensitivity analysis revealed that thickness (±10%) and elastic modulus (±5 GPa) produced the most significant changes in transmittance (0.60-0.91) and absorptance (0.70-0.91). Conclusion: Strongly an isotropic acoustic materialism offer mechanically t unable electromagnetic wave control, with thickness and elastic modulus as key design parameters. These findings provide experimental and theoretical references for high-frequency communication antennas, radar stealth coatings, and broadband absorption devices.

In this article, a Miniaturized Pentagonal Antenna (MPA) with a Minkowski Curve, Fractal Defected Ground Structure (MCF-DGS) and Frequency Selective Surface (FSS) is proposed for 5.725-5.875 GHz WLAN application. The performance of a λ/4 transmission line-fed pentagonal patch antenna is examined using an iterated MCF-DGS etched on the ground plane. In the beginning, a fundamental antenna (Antenna-1) is designed and measured at 13.2 GHz with a S₁₁ of -32.45 dB. After that, the resonant frequency of the fundamental MPA has been reduced from 13.2 GHz to 5.8 GHz by employing MCF-DGS (Antenna-2) with 56% miniaturization. The S₁₁ of MCF-DGS measured for single-band frequency 5.8 GHz is -33.36 dB. The performance attributes of an MPA with improved efficiency, peak directivity, and peak gain via MCF-DGS and FSS (Antenna-3) are also analysed. The proposed antenna of 15 × 16 mm² (or 0.29λ₀ × 0.30λ₀ mm²) with a height of h₁ = 1.6 mm is designed, produced, and tested on a substrate of FR4 epoxy. The peak gain and peak directivity at 5.8 GHz are elevated from 1.74 to 7.40 dBi and 3.53 to 7.95 dBi by using an FSS composed of FR4, with a thickness of h₂ = 1.6 mm, situated under the MPA at a height of h₃ = 8.5 mm. The prototype model's test results are validated by the predicted outcomes of the proposed model.

Reconfigurable Intelligent Surfaces (RISs) can support physical-layer security in sixth-generation (6G) vehicular networks by reconfiguring the wireless channel. However, RIS-assisted vehicular links are affected by Doppler-induced channel aging, imperfect channel state information (CSI), feedback delay, and finite-resolution phase control. This paper develops a bounded-uncertainty Doppler-Aware Robust Quantized Alternating Optimization (DA-RQ-AO) framework for secure RIS-assisted 6G vehicular communication under imperfect and delayed CSI. The system includes a multi-antenna transmitter, a legitimate receiver, a passive eavesdropper, and a roadside RIS. A robustness-aware secrecy-rate surrogate is formulated by jointly optimizing the transmit beamformer and quantized RIS phase shifts under power, unit-modulus, CSI-uncertainty, and discrete-phase constraints. The non-convex problem is addressed through alternating optimization, where the beamformer is updated using a conservative generalized eigenvector-based solution, and the RIS phase vector is refined using an explicitly derived chain-rule-based phase-gradient update followed by finite-resolution quantization with an acceptance safeguard. Numerical results show improved secrecy rate and lower secrecy outage probability than no-RIS, random-RIS, Q-AO, and robust AO benchmarks. For N=64, the proposed scheme improves secrecy rate by 118.8% over no-RIS and 73.8% over random RIS, while 2-bit RIS control shows only 5.94% loss relative to continuous phase control.