Search Results (603)

In this study, Mo/β-Ga₂O₃ vertical Schottky barrier diodes (SBDs) were fabricated using a sputtering process, and the electrical characteristics were evaluated as a function of post-annealing temperature. β-Ga₂O₃ is an ultra-wide bandgap semiconductor (UWBG) with a bandgap of about 4.8 eV and a critical breakdown field of 8 MV/cm, a promising material for high-voltage power switching applications. Mo (molybdenum) has a higher work function (~4.95 eV) than the electron affinity (~4.0 eV) of β-Ga₂O₃, its melting point (2623 °C) is higher than Pt (1768 °C) and Ni (1455 °C), so it has excellent thermal stability, and it is selected as a Schottky metal. The device is a structure in which a Si-doped β-Ga₂O₃ epitaxial layer (10 μm, N_d-N_a = 2.2 × 10¹⁶ cm⁻³) is grown on an Sn-doped β-Ga₂O₃ substrate (415 μm, N_d-N_a = 4.5 × 10¹⁸ cm⁻³). The Ti/Au (10/40 nm) was used for the back ohmic junction and Mo (300 nm) was used for the front Schottky junction. Post-annealing treatment was performed at 400, 500, and 550 °C using a rapid thermal annealing process (RTA) in an Ar gas atmosphere, and in this process, the Schottky junction and ohmic junction were formed simultaneously. Electrical characteristics including current-voltage (I–V), capacitance-voltage (C–V), Schottky barrier height (SBH), ideality factor (n), turn-on voltage (V_on), on-resistance (R_on), on/off ratio, and breakdown voltage (BV) were evaluated. No obvious Schottky characteristics were observed before post-annealing treatment, which means that As-deposited Mo does not form a rectifying junction on the β-Ga₂O₃ without post-annealing treatment. After post-annealing treatment, the I–V curve of the Schottky rectification characteristics could be confirmed under all three conditions. Among the three conditions, the device annealed at 500 °C exhibits best performance, with an SBH of 0.96 eV, n of 1.01, V_on of 0.72 V, R_on of 13.8 mΩ·cm², an on/off ratio of 10⁹, a breakdown voltage of −474 V, and a PFOM of 16.3 MW/cm². As a result of temperature-dependent I–V measurement, as chuck temperature increased, the reverse leakage current increased and SBH decreased in all devices, which is consistent with the thermally activated carrier transport. These results demonstrate that the Mo/β-Ga₂O₃ SBDs are a thermally stable contact for power device applications. Full article

Chemically induced proximity (CIP) has revolutionized small-molecule pharmacology by moving beyond traditional occupancy-based inhibition and activation. Within this paradigm, monovalent nondegrading molecular glues (ndMGs) represent a structurally compact and mechanistically distinct class of linkerless compounds. These agents stabilize or induce selective biomolecular interactions, altering the functional state or cellular localization of macromolecular complexes without causing component degradation. Once considered rare phenomena unique to specific natural products, ndMGs are now being actively engineered across diverse therapeutic landscapes, with multiple candidates advancing into clinical trials and achieving regulatory validation. We systematically highlight their evolving capabilities to modulate oncogenic networks, intervene with immune activity, rectify metabolic signaling, control neurodegenerative trafficking and stress networks, and disrupt critical pathogen assemblies, while broadening the druggable landscape into non-canonical mechanisms. In each section, we analyze the therapeutic value of the targets, the molecular mechanisms of action, the latest progress, and the unique challenges faced by these strategies. In summary, the ndMG modality represents a highly versatile strategy to unlock the undruggable proteome. Full article

The flexible DC transmission scheme based on modular multilevel converters (MMCs) is currently the mainstream solution for offshore wind power delivery. With the ongoing growth in both installed capacity and the offshore distance of wind power projects, the dimensions and weight of corresponding offshore converter stations have increased substantially. These developments present significant economic constraints and engineering challenges, thereby complicating the deployment of large-scale, long-distance offshore wind energy systems. Compared with MMCs, diode rectifier units (DRUs) offer advantages such as compact size, light weight, low cost, reduced operating losses, and high reliability. Nevertheless, DRUs lack active control capability, and conventional grid following wind turbines cannot independently support the voltage of the offshore AC network, which severely limits their application in offshore wind scenarios with stringent economic requirements. Grid forming control of wind turbines is an effective approach to address this issue. Given the widespread application of doubly-fed induction generators (DFIGs) in engineering practice and their relatively low capital costs, this study investigates the implementation of grid-forming control strategies in DFIGs to address the stability challenges of DRU-based HVDC transmission systems during fault conditions. First, the mathematical model of the DFIG is established. Then, a suitable control strategy is designed to endow the turbine with certain grid forming capabilities. Finally, the developed simulation model and control strategy are verified in PSCAD/EMTDC. The results demonstrate that the proposed grid forming DFIG control strategy can maintain stable offshore AC voltage and frequency under various fault conditions, ensure continuous and reliable operation of the DRU, and achieve fault ride through. On this basis, to account for engineering practicality and cost considerations, this study further proposes a hybrid transmission scheme combining grid-following and grid-forming DFIGs. Simulation results confirm that this hybrid scheme also achieves satisfactory operational performance, while reducing the potential cost increase associated with full-scale grid-forming retrofits, it effectively ensures fault ride-through capability and system operational stability. This method provides an effective solution for low cost, highly reliable offshore wind power DC transmission. Full article

Vehicle-side weight is a key constraint in wireless power transfer (WPT) systems for electric vehicles, as it directly affects cost, installation, and vehicle integration. This paper presents a lightweight Vehicle Assembly (VA) based on a conventional Series–Series (SS) compensation topology and a phase-shift-controlled active rectifier, designed within the SAE J2954 framework. The architecture reduces vehicle-side passive components while enabling load adaptation through the rectifier conduction angle. A fixed-output-power time-domain methodology is used to compare two operating strategies. In the exact 2-ZVS mode, only two rectifier commutations satisfy the charge-based ZVS condition, whereas in the robust 4-ZVS mode all four commutations are constrained to achieve ZVS through joint optimization of the rectifier control parameters and switching frequency. In both cases, the primary DC voltage is adjusted to maintain a constant output power of 7.7 kW. Measured coupler parameters are used in the circuit model. Across the aligned position and two measured misalignment conditions, exact 2-ZVS achieves an estimated AC–AC resonant-link efficiency of 98.01–98.41% and a modeled DC–DC efficiency of 96.16–96.90%. Robust 4-ZVS remains feasible, but its higher circulating-current requirement reduces the corresponding efficiencies to 93.26–94.96%, respectively. Therefore, for the investigated system, exact 2-ZVS provides the best efficiency–soft-switching trade-off. The AC–AC metric includes only winding and capacitor-ESR losses. The DC–DC metric additionally includes the modeled conduction and output-capacitance transition losses of the primary inverter and active rectifier; gate-drive, control, and auxiliary losses are excluded. Full article

High-capacity long-distance HVDC is indispensable for the centralized integration of deep-sea offshore wind farms and sandy-region renewable energy bases. Hybrid flexible HVDC, which adopts voltage-source converters at the sending end and current-source converters at the receiving end, meets the technical needs and potentially offers better economic efficiency in terms of converter station capital cost. However, technical challenges remain, including passive sending-end charging and start-up, joint grid formation of multiple converters, commutation failure immunity at the receiving end, and minimum continuous current maintenance. This paper proposes a hybrid flexible HVDC system scheme along with its control strategy. The scheme employs modular multilevel converters (MMCs) at the sending end and hybrid commutated converters (HCCs) at the receiving end, and a small-capacity uncontrolled diode rectifier (UDR) is configured in parallel with the HCCs. Operating characteristics of the three types of converters are analyzed, and the overall system operating strategy is presented. Electromagnetic transient simulation results show that the UDR provides a system charging circuit and can automatically supply continuous current when renewable generation power fluctuates; for bipolar HVDC or hierarchical HVDC, virtual synchronous generator control of the MMCs enables the joint grid formation and realizes the power balance between multiple converters; for faults in the receiving grid, the HCCs are able to actively turn off the valves at risk of commutation failure, ensuring a smooth ride-through. Full article

This paper reviews recent advances in integrated circuits for resonant wireless power transfer (WPT) systems in biomedical implants, with emphasis on resonant compensation networks and receiver-side power conversion. In these systems, a compact receiver coil must harvest attenuated alternating current (AC) power through biological tissue and convert it into a safe, efficient, and regulated direct current (DC) supply for implantable electronics. Limited coil size, weak coupling, load variation, and thermal safety constraints have driven the evolution from passive rectifiers to active and regulated rectifiers with delay-compensation techniques. This review first introduces the operating principles of resonant WPT links and compares series–series, series–parallel, parallel–series, and parallel–parallel compensation topologies in terms of output characteristics and implant suitability. It then summarizes passive, cross-coupled, active full-wave, delay-compensated, and regulated rectifiers. Finally, design guidelines are provided for selecting compensation and rectifier architectures according to power level, coupling condition, operating frequency, integration complexity, and regulation requirements. Full article

Background: Large yellow tea (LYT), a distinctive variety made from mature leaves, has recently gained attention for its remarkable health benefits. However, whether these benefits can be transmitted from mother to offspring remains unexplored. Purpose: This study investigated whether maternal LYT consumption confers intergenerational protection against metabolic and behavioral disorders induced by perinatal bisphenol A (BPA) exposure in F1 offspring. Methods: A mouse model of perinatal BPA exposure (0.03% in diet) was established with or without maternal LYT supplementation (2.5% in diet). Metabolic parameters were assessed through biochemical assays and gene expression analysis (RT-PCR). Energy expenditure and spontaneous activity were monitored using a Comprehensive Lab Animal Monitoring System (CLAMS). Hippocampal proteomic profiling was performed using label-free quantitative proteomics. Results: LYT significantly reduced maternal BPA body burden, potentially via limiting absorption, enhancing glucuronidation metabolism, and promoting excretion. Notably, LYT exhibited bidirectional metabolic regulation, alleviating gestational hyperglycemia in dams while restoring hypoglycemia in offspring, and normalizing underweight and hypolipidemia. Mechanistically, the SIRT6 (sirtuin 6)/FOXO1 and SIRT6/SREBP1 pathways may be involved in regulating gluconeogenesis and lipogenesis. Concurrently, LYT rectified BPA-induced hyperactivity and reduced excessive energy expenditure. Proteomic analysis revealed that LYT partially restores BPA-induced dysregulation of cholesterol metabolism and glutamatergic/GABAergic synaptic pathways, which may contribute to rebalancing synaptic homeostasis. Conclusions: These findings suggest that maternal LYT supplementation confers intergenerational protection against BPA-induced metabolic and behavioral disorders in mice, potentially acting through enhanced toxin clearance, bidirectional metabolic regulation, behavioral normalization, and partial restoration of hippocampal synaptic homeostasis. This study provides a theoretical basis for developing natural dietary interventions to mitigate developmental toxicant-induced health risks. Full article

This paper presents the experimental validation of a high-frequency full-SiC railway auxiliary converter power module intended as a building block for modular multi-system railway auxiliary converters. The proposed architecture employs a unified SiC-based power conversion platform that integrates an active front-end single-phase PWM rectifier with a galvanically isolated high-frequency DC/DC stage operating at 90 kHz under zero-current switching (ZCS) conditions. Although the converter is designed for both AC and DC traction systems, this study focuses primarily on its operation under single-phase AC railway supply conditions, which are representative of practical applications. A hybrid bipolar–unipolar modulation strategy is used to reduce the RMS voltage stress on the input inductor while preserving controllability of the input current near the voltage zero-crossing regions. Special attention is given to operation under distorted railway supply voltages, which are common in real traction systems. The control structure combines a proportional–resonant (PR) current controller, harmonic compensators, feedforward voltage compensation, and MSOGI-based synchronization to ensure stable synchronization and low-input current distortion even under non-ideal conditions. Experimental validation was performed on a 10 kW laboratory prototype. The results demonstrate a peak efficiency of 98.4% and near-unity input power factor. Under heavily distorted supply conditions ${\mathrm{THD}}_{\mathrm{v}}>30\%$, the input current distortion remained below ${\mathrm{THD}}_{\mathrm{i}}=2.3\%$. Harmonic and STFT analyses confirmed the robustness of the proposed synchronization and current control structure. The obtained results indicate that the proposed high-frequency full-SiC converter topology is a promising solution for future modular railway auxiliary converters, offering high efficiency, reduced passive component volume, and high power density. Full-scale high-voltage validation under both AC and DC traction systems remains the subject of further work. Full article

This paper presents a high-efficiency direct-AC LED driver integrating a 14-stage voltage-segmented architecture, digitally coordinated stage selection, and adaptive current-reference regulation. The proposed driver provides finer matching between the rectified bus voltage and the cumulative LED voltage, thereby reducing the residual voltage and power dissipation of the linear regulating devices. Unlike conventional constant-current segmented drivers, the current reference is adjusted according to the selected operating state and the corresponding active LED voltage. A valley-filler circuit is employed to extend the conduction interval of the LED driver and reduce the low-voltage dead zone. A prototype operated at an input voltage of 112.92 V AC and a rated power of approximately 12 W was experimentally evaluated. The measured input power, total LED active power, conversion efficiency, and power factor were 12.12 W, 11.54 W, 95.18%, and 0.9, respectively. The results demonstrate that finer voltage segmentation can reduce voltage-mismatch loss, although the increased number of stages introduces additional component and control complexity. Full article

Polycyclic aromatic hydrocarbons (PAHs) from the water-soluble fraction (WSF) of crude oil are recognized cardiotoxicants in fish; however, all electrophysiological evidence to date derives from acute exposure experiments. This study examined the effects of prolonged (5–8 h) incubation of isolated ventricular cardiomyocytes from the navaga cod (Eleginus nawaga, Walbaum, 1792) with 10% WSF (total dissolved tricyclic-PAH concentration in the tens-of-nM), 3 µM phenanthrene (Phe), or 3 µM 3-methylphenanthrene (3-MP) on action potential (AP) parameters and the underlying ionic currents using the whole-cell patch-clamp technique. WSF and 3-MP reduced AP amplitude and maximum rate of depolarization through suppression of the fast sodium current (I_Na), whereas Phe and 3-MP shortened AP duration, associated with decreased density and a hyperpolarizing shift in steady-state activation of the rapid delayed rectifier potassium current (I_Kr). The L-type calcium current and inward rectifier potassium current remained unaffected by all treatments. Notably, the effects of prolonged incubation differed qualitatively from previously reported acute responses to the same compounds, suggesting the involvement of indirect mechanisms such as reactive oxygen species production and activation of intracellular signaling cascades. These findings demonstrate that subchronic PAH exposure produces distinct and potentially proarrhythmogenic alterations in fish cardiac electrophysiology that cannot be predicted from acute exposure data alone. Full article

Precise brain tumour delineation is vital for therapy protocols and tracking. However, standard Rectified Linear Units (ReLU) struggle to capture subtle necrotic-core variations due to zero-gradient behaviour in the negative domain. To address this, we present a controlled benchmark of 12 activation functions within a fixed Residual 3D U-Net using the Brain Tumour Segmentation (BraTS) 2020 dataset. In the single-run benchmark, Swish achieved the best necrotic-core (NCR) Dice (0.676; +2.0% over ReLU, p < 0.01), while TanhExp attained the highest whole-tumour accuracy (0.879). To test the reliability of these single-run results, the four functions central to our claims were retrained across three random seeds. This analysis confirmed a small but consistent NCR advantage for the smooth and adaptive functions—Swish (0.677 ± 0.003) and PReLU (0.678 ± 0.004) over ReLU (0.661 ± 0.012; pooled p < 0.001)—with Swish among the most stable functions in this region. By contrast, the apparent single-run differences in the enhancing tumour, and the underperformance of PReLU, did not generalise across seeds, indicating that activation-function effects in this task are concentrated in the necrotic core and that single-seed comparisons can be misleading. Crucially, Swish achieved these gains with zero additional trainable parameters and only a ~1% training latency penalty on common hardware. Replacing ReLU with Swish offers a cost-effective, architecture-preserving strategy to improve segmentation reliability and boundary delineation. Ultimately, this zero-cost architectural modification is a promising, preliminary step towards more reliable automated tumour delineation, pending prospective validation on multi-institutional data and expert radiological assessment. Full article

Generator-side transient overvoltage may occur in DC 600 V AC–DC–AC railway power supply systems because switching-induced common-mode voltage generated by the front-end rectifier can propagate in reverse through cable distributed parameters, grounding impedance, and generator parasitic capacitance. Although AZSVPWM has been widely studied as a common-mode voltage reduction technique, its application to the suppression of generator-side reverse transient overvoltage in railway DC 600 V power supply systems has not been sufficiently investigated. In this paper, AZSVPWM is applied to the front-end active rectifier as a source-side suppression strategy. A high-frequency electromagnetic transient model is developed by considering the generator equivalent impedance, cable distributed parameters, grounding path, and generator winding-to-ground parasitic capacitance. The model is validated by comparing simulated and measured generator terminal voltages under AZSVPWM operation. Based on this model, the common-mode voltage excitation mechanism, reverse propagation path, and overvoltage suppression effect of AZSVPWM are analyzed. The results show that, compared with conventional SVPWM under identical active-rectifier conditions, AZSVPWM reduces the representative peak transient voltage at the generator terminals from 751.37 V to 557.71 V under the 8 m cable condition, corresponding to a reduction of approximately 25.77%. In addition, AZSVPWM-based active rectification improves the low-frequency voltage quality compared with conventional thyristor rectification, and the THD is estimated to decrease from approximately 14.8% to 0.8% based on the FFT spectrum. Parametric analysis further shows that AZSVPWM maintains stable suppression performance for cable lengths of 2–15 m and generator parasitic capacitances of 5–20 nF, with the maximum peak-voltage deviation caused by parasitic capacitance variation being approximately 1.15%. These results indicate that AZSVPWM provides a practical and robust source-side suppression strategy for generator-side transient overvoltage in railway DC 600 V power supply systems. Full article

To address the current issues of single-objective control and the inability to achieve coordinated operation between the Modular Multilevel Converter (MMC) and the thyristor rectifier in parallel-type ice melting systems, this paper proposes a master-slave coordinated control method for such systems. The MMC operates in constant PQ mode, while the thyristor rectifier operates in constant-voltage mode. The thyristor rectifier provides voltage support to the MMC, and an adaptive U-I droop control is introduced in the control loop to cope with voltage drop. The MMC adjusts its active power output according to the operating condition of the thyristor rectifier, enabling coordinated ice melting operation, while simultaneously performing reactive power compensation and active filtering for the system. This paper elucidates the operating principle of the ice melting system, analyzes its harmonic characteristics, designs a control strategy, and constructs a PSCAD 5.0 simulation model to validate the proposed control strategy. The results demonstrate that the proposed strategy can coordinate the active power allocation between the MMC and the thyristor rectifier, laying the foundation for the safe and stable operation of the ice melting system while suppressing the harmonic currents and reactive power introduced into the power grid by the thyristor ice melting system. Full article

Power-quality degradation caused by nonlinear loads remains a critical challenge in sustainable low-voltage distribution systems, as it increases harmonic distortion, reactive power circulation, feeder losses, and thermal stress in network assets. This paper evaluates a discontinuous-conduction-mode (DCM) Cuk-based power factor correction (PFC) scheme integrated with a silicon-controlled rectifier (SCR) stage to improve power quality in a radial distribution feeder. The IEEE 13-bus distribution test system is used as the benchmark network, with the nonlinear load connected at node 634, supplied through a 4.16/0.48 kV transformer. Two operating scenarios are compared, an uncompensated case and a compensated case, using the SCR–Cuk PFC structure. The assessment considers source-side voltage and current waveforms, power factor, total harmonic distortion (THD), voltage deviation, nodal harmonic propagation, active and reactive power flows, and line losses. The results show that the proposed scheme increases the source-side power factor from 0.431 to 0.99 and reduces the source current THD from 16.31% to 1.10%, meeting the source-side 5% harmonic reference level used in this study. At the network level, the THD at node 634 decreases from 17.12% to 6.23%, while the main affected feeders show relevant reductions in active and reactive losses. These findings indicate that localized active PFC can support more sustainable distribution system operation by improving power quality and reducing losses. However, feeder-wide harmonic compliance may require distributed compensation at additional harmonic-sensitive nodes. Full article

Distributed-drive all-wheel steering (AWS) six-axle vehicles possess distinct advantages in power performance, maneuverability, and environmental adaptability. However, when navigating tight curves under sudden low-friction road conditions, their inherent long wheelbase and strong inter-axle coupling typically lead to compromised spatial maneuverability, trajectory decoupling between the vehicle nose and tail, and lateral dynamic instability. To resolve these critical issues, this paper proposes a geometry–dynamics coupled lateral control scheme with adaptive speed planning for six-axle vehicles under confined spatial and low-friction conditions by seamlessly fusing a dual-point preview mechanism with multi-mode steering mappings. First, a three-degree-of-freedom nonlinear vehicle dynamic model incorporating longitudinal, lateral, and yaw motions is constructed, alongside the formulation of extended Ackermann kinematic steering manifolds for three distinct modes: rear-axle steering, center steering, and crab steering. To rectify the kinematic under-constrained deficiency inherent in conventional single-point preview path-tracking architectures, a joint front-and-rear dual-point preview constraint mechanism is established. This framework permits the quantitative derivation of a spatial geometric reconstruction method for the instantaneous center of rotation (ICR), which algebraically maps the ideal ICR trajectory requirements onto the physical constraints of the selected steering modes. Consequently, complete geometric constraints on both the front and rear trajectories are achieved, enabling active compression of the vehicle’s turning radius. Furthermore, to handle sudden low-friction disturbances, road adhesion limits and vehicle lateral stability boundaries are explicitly incorporated to design a multi-scale adaptive preview distance dynamic scaling mechanism driven by dynamic safety margin corrections. By adaptively scaling the spatial constraint at the geometric layer, this mechanism proactively mitigates nonlinear tire sideslip force saturation via feedforward action, thereby preventing tracking divergence and catastrophic sideslip instability under physical adhesion limits. Co-simulations based on the high-fidelity TruckSim-Simulink platform demonstrate that, in standard curves, the proposed dual-point preview manifold fusion strategy reduces the minimum turning radius by 9.6–10.1% and shortens the cornering transit time by 7.5% compared with the traditional single-point preview mechanism. By actively constraining the front and rear trajectories, the trajectory decoupling between the vehicle nose and tail is effectively resolved. Under narrow-lane scenarios, the maximum lateral error is restricted within 0.78 m, representing a 37.6% reduction relative to the single-point preview, while the maximum steering angle of the front axle is compressed by approximately 18%, thereby significantly improving spatial passability and preventing intermediate body interference. Most notably, under low-friction surface disturbances, the dynamic-margin-corrected adaptive preview adjustment mechanism exhibits remarkable robustness, constraining the maximum lateral tracking error to within 0.68 m. The proposed geometry–dynamics coupled lateral control strategy successfully elevates the tight-curve maneuverability of heavy transport vehicles while concurrently reinforcing their lateral dynamic stability under limit combined spatial and adhesion constraints. Full article