Search Results (1,428)

Biosurfactants are environmentally friendly surface-active compounds with promising applications in environmental remediation. In this study, a biosurfactant-producing bacterium, Bacillus (B.) velezensis SHB.28, was isolated from heavy metal-contaminated soil and evaluated for its ability to produce biosurfactants using date syrup as a low-cost agro-industrial substrate. Screening assays including drop-collapse (DC), oil spreading (OS), and emulsification index after 24 h E₂₄ (%) confirmed strong biosurfactant production. Culture conditions were optimized, revealing that 30 °C, pH 6, and a C/N ratio between 10% and 20% provided optimal production. Under optimized conditions, the crude biosurfactant extract yield reached 2.16 g/L within 24 h, accompanied by a reduction in surface tension from 69 to 29.1 dyn/cm and high emulsification activity. Kinetic modeling showed that emulsification activity followed an exponential growth model (R² = 0.985), whereas surface tension dynamics were well described by a spike decay–plateau model (R² = 0.998). Structural characterization using Fourier-transform infrared spectroscopy (FTIR), electrospray ionization–mass spectrometry (ESI–MS), and nuclear magnetic resonance (NMR) spectroscopy revealed that the biosurfactants are surfactin- and iturin-like cyclic lipopeptides composed of a β-hydroxy fatty acid chain (C₁₃–C₁₅) linked to a cyclic peptide moiety. The biosurfactant exhibited a critical micelle concentration of 100 mg/L and an anionic character with a pH_pzc of 5.7. Furthermore, it demonstrated high efficiency in removing heavy metals, achieving removal efficiencies of 99.88% for Fe²⁺, 99.69% for Pb²⁺, and 94.72% for Cu²⁺, outperforming conventional surfactants such as SDS and Tween 80. These findings highlight the potential of date syrup-derived surfactin and iturin from B. velezensis SHB.28 as sustainable and efficient biosurfactants for environmental remediation and heavy metal removal applications. Full article

Background: Influenza remains a significant global public health threat, causing substantial morbidity and mortality worldwide. While vaccination serves as the best preventive strategy, considerable interindividual variability in vaccine-induced immune responses persists. The ZBTB46 rs2281929 polymorphism (c.A31G; p.T11A; ACG>GCG), which corresponds to the evolutionarily conserved mouse mutation Zbtb46^T11A (c.A31G; ACT>GCT), has been associated with enhanced antibody responses to influenza vaccination in humans, though its functional mechanisms remain unknown. This study aimed to investigate how this mutation affects influenza vaccine immunogenicity using a knock-in mouse model. Methods: A Zbtb46^T11A knock-in mouse model was generated using CRISPR/Cas9 technology. Homozygous (HO) and wild-type (WT) mice were immunized with a quadrivalent influenza vaccine in a prime-boost regimen. Humoral immune responses were assessed by Enzyme-linked immunosorbent assay, hemagglutination inhibition (HI), and microneutralization (MN) assays. Antibody-secreting cells (ASCs) were quantified by Enzyme-linked immunospot assays. Germinal center B cells, plasma cells, plasmablast cells, conventional dendritic cell (cDC) subsets, and T helper (Th) cells were analyzed by flow cytometry. Statistical comparisons were performed using a two-sample t-test. Results: The Zbtb46^T11A mutation did not alter Zbtb46 protein expression or its abundance in cDCs. Following vaccination, HO mice exhibited significantly enhanced humoral responses, including higher HA-specific IgG titers, HI and MN antibody levels, and increased numbers of ASCs. Flow cytometry revealed elevated proportions of germinal center B cells and plasma cells in HO mice. Furthermore, HO mice showed a selective expansion of type 1 cDCs (cDC1s) and a concomitant increase in Th1 cell frequencies and IFN-γ-secreting cells, while cDC2 proportions and Th2 responses remained unchanged. Conclusions: The Zbtb46^T11A mutation is associated with enhanced influenza vaccine immunogenicity, concomitant with increased cDC1 proportions, Th1 polarization, and germinal center-dependent humoral immunity. These observed associations suggest a candidate mechanism whereby Zbtb46 modulation may shape adaptive immunity, though further functional studies are required to establish causality. These findings provide insights into host genetic variation in vaccine responsiveness and may inform personalized vaccination strategies. Full article

The increasing demand for electrified rail transportation has intensified power quality (PQ) challenges, including harmonics, voltage imbalance, and low power factor (PF). These issues have driven the development of advanced traction power supply systems, particularly co-phase configurations, to improve power quality, enhance grid-connected stability, and strengthen the operational resilience of railway power infrastructure. This paper proposes a co-phase power supply system for high-speed railways that facilitates high-speed train operation by integrating power quality compensation technologies while reducing the required number of neutral sections by half, thereby improving the continuity and robustness of traction power delivery. To address PQ issues, a capacitive-coupled hybrid power quality conditioner (HPQC) incorporating renewable energy sources (RESs) into its DC link is introduced. Given the highly dynamic and time-varying nature of railway loads, a sliding mode control (SMC)-based robust control method is developed based on the state space model of the co-phase power supply system and the HPQC to provide a stable and rapid response to load variations and operational disturbances. The effectiveness and real-time implementation capability of the proposed approach are validated through real-time control hardware-in-the-loop (CHIL) simulations. Results from MATLAB/Simulink simulations and real-time CHIL testing demonstrate substantial harmonic reduction, improved power factor, reduced negative-sequence currents, and enhanced overall system efficiency. These outcomes confirm the suitability of the proposed system for modern high-speed railway applications and highlight its contribution to resilient traction power supply systems capable of maintaining reliable operation under highly variable loading conditions. Full article

Parkinson’s disease (PD) involves progressive basal ganglia dysfunction, with hyperexcitability of striatal indirect-pathway D2 medium spiny neurons (D2-MSNs) linked to motor impairment. Neuromotor rehabilitation is an important therapy, but its efficacy varies across interventions. This thematic review examines eleven rehabilitative strategies for PD, spanning forced and voluntary exercise (FE and VE respectively), non-invasive brain stimulation (rTMS, tDCS), and technology-based approaches such as exoskeletons, augmented reality, and dual-task training, within a framework distinguishing striatal recalibration from compensation via alternative motor networks. To formalize this distinction, a Bayesian ranking framework combines neurobiological plausibility with clinical evidence quality, identifying three functional clusters: a high-recalibration cluster (FE, p ≈ 0.80; LSVT BIG, p ≈ 0.62), an intermediate-uncertainty cluster (rTMS, HIIT, tDCS, treadmill, resistance training, Tai Chi/dance; 0.40–0.56), and a bypass/compensatory cluster (augmented reality, exoskeletons, dual-task training; p ≤ 0.33). This distinction between direct modulation of basal ganglia circuitry and recruitment of alternative motor networks, including the lateral premotor cortex, parieto-premotor circuits, and cerebello-thalamo-cortical pathways, supports a precision rehabilitation approach in PD. Full article

Open-end-winding dual-inverter converters are attractive for high-voltage and high-power photovoltaic–energy storage systems because of their multilevel output capability and high DC-link voltage utilization. However, unequal power availability between the independent DC links may cause one inverter to exceed its linear modulation range, resulting in overmodulation and grid-current distortion. This paper proposes a power-sharing strategy based on reference-voltage-vector reconstruction for a dual-inverter system with a DC-link voltage ratio of 2:1. The equivalent four-level output characteristics are analyzed, and the feasible power-sharing range is derived according to the modulation index, DC-link voltages, and inverter voltage limits. Combined with 180° decoupled modulation, the proposed strategy enables flexible power transfer among the photovoltaic unit, energy storage system, and grid while keeping both inverters within the linear modulation region. OPAL-RT results demonstrate stable operation under different power-sharing modes, with the grid-side power maintained at approximately 23.2–24.1 kW. These results verify the effectiveness and feasibility of the proposed strategy. Full article

The direct stator connection of a doubly fed induction generator (DFIG) makes it highly sensitive to grid-voltage disturbances. Although a supercapacitor-supported dynamic voltage restorer (SC-DVR) can restore the machine-terminal voltage, assigning the entire fault-induced power imbalance to the supercapacitor increases the required storage capacity. To address this problem, an adaptive coordinated fault ride-through control strategy is proposed for a DFIG–SC-DVR wind–storage system. A unified dynamic model is first established to describe the electromagnetic response, dc-link energy imbalance, rotor kinetic-energy exchange, and series voltage compensation under symmetrical and asymmetrical voltage sags. The remaining adjustable kinetic-energy margin of the rotor and the remaining adjustable energy margin of the supercapacitor are then used to construct an online coordination coefficient. Accordingly, the active-power references of the DFIG and SC-DVR are dynamically adjusted to match their instantaneous regulation capabilities. Time-domain simulations show that the proposed strategy maintains the machine-terminal voltage and keeps the rotor current, dc-link voltage, and rotor speed within prescribed limits. Compared with non-coordinated control, it reduces the SC-DVR absorbed energy by 51.43% and 57.72% under symmetrical and asymmetrical faults, respectively; compared with fixed-ratio coordination, the corresponding reductions are 34.69% and 29.81%. Supplementary sweeps over wind speeds of 10–12 m/s and short-circuit ratios of 2–10 further verify the bounded applicability of the method without retuning the controller. Full article

Al₂O₃ and SiO₂ nanofillers have been widely used to improve the insulation performance of cross-linked polyethylene (XLPE) for high-voltage power cables. In this work, XLPE nanocomposites containing 3 wt.% Al₂O₃ or SiO₂ were prepared to compare the effects of the two nanofillers on the thermal, mechanical, and electrical properties of XLPE. Hydrophobic surface treatment was applied to improve nanofiller compatibility with the polymer matrix. Differential scanning calorimetry and thermogravimetric analysis were used to evaluate crystallinity and thermal stability. Tensile and creep tests were performed to assess mechanical behaviour, while volume resistivity, dielectric constant, and breakdown strength under AC, DC, and DC polarity-reversal fields were measured at 30 °C and 90 °C. The results showed that Al₂O₃-filled XLPE had higher crystallinity and a higher initial decomposition temperature than SiO₂-filled XLPE, together with lower creep elongation, indicating better thermal and dimensional stability. In contrast, SiO₂-filled XLPE exhibited higher elongation at break, a lower power-frequency dielectric constant, and improved breakdown strength. Hydrophobic surface treatment increased volume resistivity and breakdown strength and reduced data dispersion for both nanocomposites, suggesting that improved interfacial compatibility and more homogeneous microstructures contributed to performance enhancement. Overall, Al₂O₃ mainly improved thermal endurance and creep resistance, whereas SiO₂ was more effective in enhancing dielectric and mechanical properties. These findings provide guidance for selecting nanofillers for XLPE nanocomposite insulation in high-voltage cable applications. Full article

Power-electronic converter control is a key issue in the weak-grid integration of doubly fed induction generator (DFIG)-based offshore wind farms. In conventional fixed-reference DFIG control, the rotor-side power command is usually treated as a tracking target, although its suitability may change with the present point of common coupling (PCC) voltage and phase-angle condition. This paper proposes a weak-grid dynamic sensitivity-based model reference governor (WG-DSMRG) for DFIG offshore wind-farm converter control. The governor is inserted upstream of the RSC power-reference path, while the conventional RSC/GSC current controllers, phase-locked loop (PLL), coordinate transformations, and modulation structure are retained. The short-horizon relation between wind-farm power variation and PCC voltage-angle response is estimated from measured electrical signals. The RSC power command is then corrected through weak-grid scheduling and converter-capability projection. A 60-MW offshore DFIG wind farm connected to a weak AC grid is tested under an upstream voltage sag and a PCC single-line-to-ground fault. In the tested cases, the PCC reactive-power peak decreases from about 3.5 Mvar to 2.5 Mvar, and the DC-link voltage peak is reduced under both disturbances. The evaluated PCC voltage and current THD values are also lower with the proposed controller. These results show that reference-layer correction can improve weak-grid integration and power quality without replacing the established DFIG converter-control platform. Full article

Reliable integration of wind energy into modern power grids requires control strategies capable of maintaining stable operation under stochastic wind conditions and grid-side disturbances. This paper presents an adaptive metaheuristic optimization and numerical modeling framework for robust multi-scenario tuning of proportional–integral controller parameters in a doubly fed induction generator (DFIG)-based wind-energy conversion system. The optimized control loops include the rotor-side converter, grid-side converter, rotor-speed loop, and DC-link voltage loop. Unlike conventional tuning approaches that rely on nominal operating points or limited deterministic cases, the proposed formulation evaluates each candidate controller over multiple operating scenarios, including start-up dynamics, step wind-speed variation, random wind fluctuation, and grid-voltage dip conditions. An Adaptive Whale Optimization Algorithm (AWOA) is developed by incorporating diversity-aware adaptation and stagnation-handling mechanisms into the standard WOA structure to improve the exploration–exploitation balance during the search process. The tuning objective combines aggregate transient-performance minimization with robustness-oriented scenario evaluation, thereby promoting controller gains that remain effective across uncertain operating conditions. Comparative numerical simulations against Grey Wolf Optimizer, Generalized Grey Wolf Optimizer, Moth-Flame Optimizer, and standard WOA show that the proposed AWOA achieves lower aggregate Integral Time Squared Error values across the considered cases. Convergence assessment, ablation analysis, and hold-out robustness testing further confirm the contribution of the adaptive mechanisms. Time-domain responses also demonstrate improved DC-link voltage regulation and reactive-power recovery under severe grid disturbances. These results indicate that the proposed framework can enhance the reliability and resilience of grid-connected DFIG wind-energy systems, supporting more robust and sustainable renewable-energy integration. Full article

On model predictive control, the weighting factors are often challenging to tune, which usually relies on trial-and-error methods. To bypass this inconvenience, this paper enhances a previously proposed weightless method applied to Finite Control Set Model Predictive Control (FCS-MPC). An induction motor driven by a neutral point clamped inverter on a Back-to-Back configuration, connected to the grid and allowing power regeneration is presented. On the control side, a weightless predictive current control is presented along with a novel strategy to build the torque reference based on the motor dynamics, which can also dismiss load torque measurement or estimation with a speed deviation lower than 0.1%. To ensure reliable results, the power circuit was assembled on a hardware-in-the-loop environment, whilst the control was embedded on a digital signal processor, bringing the simulation closer to a real power plant. Simulation results proved that the strategy could regulate the Direct Current (DC) link voltage and the rotor speed and that the machine still operates on all four quadrants with a power factor close to unity. The mean absolute percentage error presented during full load was 0.12% for the DC link voltage and 0.22% for the rotor speed. For the grid current, the Total Harmonic Distortion (THD) obtained is 1.00% during pre-charge of the DC link capacitors, whilst for the stator current, it was 0.76% during full load. The control strategy also proved to be more efficient than previous works and presented robustness under many parameters mismatching. Full article

With the increasing penetration of distributed generation, electric vehicles and single-phase loads in the low-voltage distribution network, flexible interconnected systems face more prominent three-phase unbalance and direct-current (DC)-side voltage regulation problems. Unbalanced loads not only lead to asymmetry of alternating current (AC)-side voltage and current but also introduce low-frequency ripples into the common DC bus through the power-coupling relationship and further cause the neutral-point potential shift of the split capacitors. To address these problems, this paper takes a double-ended flexible interconnection system with an integrated three-level Buck–Boost energy storage interface as the research object and proposes a DC-side total-voltage-neutral-point cooperative control strategy. Firstly, the coupling relationship between AC-side power fluctuation and DC-side voltage state under unbalanced conditions is established to analyze the formation mechanism of DC bus low-frequency ripple and neutral-point potential offset; secondly, based on the neutral-point access characteristic of three-level Buck–Boost, the DC-side modulation quantity is decomposed into a common-mode duty cycle and a differential-mode duty cycle. Among them, the common-mode duty cycle is used to regulate the total power exchange on the energy storage side to achieve DC bus total voltage maintenance and low-frequency ripple suppression; the differential-mode duty cycle is used to regulate the difference between the duty cycles of the upper and lower half-bridges to achieve capacitor charging and discharging distribution regulation and neutral-point potential balance. Finally, a simulation model is built to verify the proposed control strategy. The simulation results show that the proposed method is able to stabilize the DC bus voltage around 800 V under power step disturbance and suppress the midpoint voltage deviation from a low-frequency oscillation of about 10 V to within about ±1 V. This verifies the effectiveness of the control strategy under unbalanced load and power disturbance conditions. 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

The efficacy of low-carbon power systems is reduced by the high energy demand of conventional CO₂ capture processes, the loss of recoverable thermal energy, and power-quality disturbances associated with variable renewable generation. This study suggests an integrated framework that integrates membrane-assisted CO₂ capture, thermoelectric waste-heat recovery, photovoltaic generation, battery energy storage, and a grid-connected converter to address these issues. During the capture of CO₂, the waste heat is converted into electrical energy using a thermoelectric generator and integrated with the photovoltaic and battery outputs through a common DC link. A conventional phase-locked loop is not necessary for reference-signal extraction, DC-offset rejection, harmonic compensation, and power management, as an Enhanced Notch Filter-Based Second-Order Generalized Integrator (ENF-SOGI) controller is employed. The effectiveness of the proposed system is demonstrated by simulation and experimental studies conducted under variable irradiance, nonlinear loading, distorted-load, and distorted-grid-voltage conditions. The membrane unit achieves a CO₂ capture efficiency of approximately 92%, with a specific energy consumption of 1.2 GJ/tCO₂. The controller reduces the source-current total harmonic distortion from 24.3% to approximately 1.2–1.3%, limits its experimental variation to ±5 V, and maintains the DC-link voltage at approximately 600 V. Consequently, the proposed architecture is designed to facilitate low-carbon grid operation by integrating a unified energy-management system that includes high-efficiency CO₂ separation, the productive recovery of waste heat from the capture process, increased renewable energy utilization, and IEEE-compliant source-current quality. Full article

A unified power quality conditioner (UPQC) is developed for the mitigation of grid-voltage and -current distortions under steady-state and dynamic conditions. The proposed configuration integrates series and shunt inverters through a common DC-link capacitor. The capacitor functions as an energy buffer by accommodating the power exchanged between the two inverters. Following an abrupt grid-voltage disturbance or load transition, the DC-link capacitor must instantaneously deliver or absorb power to maintain the power balance between the inverters while sustaining the required compensation. The resulting transient energy exchange can produce pronounced DC-link voltage excursions, with adverse consequences for system stability and compensation accuracy. Rapid and accurate regulation of the DC-link voltage is therefore essential for maintaining the dynamic compensation performance of the UPQC. To improve this regulation, a compensatory wavelet fuzzy neural network incorporating asymmetric membership functions (CWFNN-AMFs) is introduced in place of the conventional proportional–integral (PI) controller. The network architecture and its online learning algorithm are derived in detail. Finally, experimental results under steady-state and dynamic conditions demonstrate that the CWFNN-AMF-controlled UPQC improves both power quality compensation and DC-link voltage regulation, thereby verifying the feasibility and effectiveness of the proposed control framework. Full article

The rapid electrification of transportation has accelerated the demand for high-power electric vehicle (EV)-charging systems with high efficiency, compact size, galvanic isolation, and flexible scalability. Conventional isolated EV chargers typically adopt cascaded AC–DC and DC–DC conversion stages, which require additional semiconductor devices, passive components, and bulky dc-link capacitors, thereby increasing system complexity and limiting power density. This paper proposes a scalable three-phase modular parallel quasi-single-stage isolated single-ended primary-inductor converter (SEPIC) for high-power EV fast-charging applications. The proposed converter integrates power factor correction, voltage regulation, and high-frequency isolation within a unified SEPIC-based conversion cell, eliminating the intermediate dc-link capacitor while reducing the number of magnetic components and power conversion stages. By employing a Δ-connected three-phase input and input/output-parallel modular configuration, the proposed architecture provides a flexible power expansion approach based on a 9 kW basic module, with the potential to extend to higher power levels, such as 54 kW, through paralleling multiple identical modules. The operating principle, steady-state characteristics, continuous conduction mode (CCM)/discontinuous conduction mode (DCM) transition mechanism, current-sharing behavior, and control strategy are systematically investigated. An 18 kW prototype consisting of two parallel modules is experimentally validated under 380 V three-phase AC input and 400 V DC output conditions. The experimental results demonstrate a peak efficiency of 97.5%, a rated efficiency of 97.3%, a power factor (PF) of 0.999, and an input current total harmonic distortion (THD) of 2.55%, confirming the effectiveness and scalability of the proposed converter for high-power EV fast-charging applications. Full article