Search Results (652)

A new control method for efficiency optimization in systems composed of parallel converters is presented in this paper. The proposed methodology considers the individual efficiency surfaces for given ratings of power and voltage and determines the optimum operating point for each converter such that the global system efficiency is maximized throughout the entire operating spectrum. Furthermore, a supervisory control strategy is proposed to manage the power-sharing of the converters according to the optimal surfaces provided by the methodology, enabling a performance enhancement for the system by improving its efficiency. Different approaches can be used to implement the active current sharing (ACS) scheme, and in-depth discussions are provided to guide the designer through the tradeoffs to achieve the desired transient and steady-state behavior for the system. Experimental results show that under light load operation, an improvement of 8.5% is achieved in comparison with a conventional technique of equal power-sharing. This points out that the proposed strategy is especially applicable and can significantly improve the performance of systems powered by batteries or renewable sources. Full article

This work uses battery-coupled power electronic converter systems and distributed backstepping controllers to improve the reliability of electrical distribution networks. The motivation is to prevent blackouts such as the 28 April 2025 outage in Spain, Portugal, and the south of France. It is now accepted that a rapid rise in solar power injections caused AC overvoltage above grid code limits, triggering photovoltaic (PV) park disconnections as overvoltage self-protection. This case study considers near-Zero-Energy Buildings (nZEBs) connected to the Madeira Island isolated microgrid, where PV power installation is increasing excessively. The main university facility will be upgraded as an nZEB, using roughly 3000 m² of unshaded rooftops plus coverable parking areas to install PV panels. Optimizing the profits/energy cost ratio, a PV power system of around 560 kW can be planned, and the Battery Storage System (BSS) energy capacity can be estimated. The BSS is connected to the university nZEB via backstepping-controlled multilevel converters to manage PV and BSS, enabling the building to contribute to voltage and frequency regulation. Distributed multilevel converters inject renewable energy into the medium-voltage network, regulating active and reactive power to prevent overvoltages shutting down the PV inverters. This removes sustained overvoltage and maximizes PV penetration while augmenting AC grid reliability and resilience. When there is excess solar power and reactive power is insufficient to reduce voltage, controllers slightly curtail PV active power to eliminate overvoltage, maintaining operation with minimal revenue loss while preventing long interruptions, thereby improving grid reliability and power quality. Full article

In the aviation sector, there is a growing demand for high-specific-power electrical machines to realize More Electric Aircraft (MEA). The goals for these machines were set by the National Aeronautics and Space Administration (NASA) as 1 $\mathrm{M}$$\mathrm{W}$ power, >13 kW kg⁻¹ of power density, and efficiency >96%. To address these requirements, this paper proposes an electromagnetic design of a high-speed, power-dense, 1 $\mathrm{M}$$\mathrm{W}$ radial-flux Permanent Magnet Synchronous Machine (PMSM) for aerospace propulsion applications that achieves NASA targets. Achieving high-specific-power objectives necessitates geometry optimization that simultaneously minimizes motor mass while maximizing output power. This paper presents a faster optimization algorithm that hybridizes Genetic Algorithm and Artificial Neural Network (ANN)-based surrogate modeling to optimize the motor for multi-objective goals. The proposed framework employs a multi-objective approach targeting maximum torque output and efficiency within a minimum motor mass. This approach, using an ANN-based surrogate, significantly reduces optimization time by saving 95% of the time compared to FEM simulations. The optimized 1 $\mathrm{M}$$\mathrm{W}$ motor attains 98% efficiency and an active power density of 24.87 kW kg⁻¹. The various stages of the optimization are presented in detail and a comparison of the time saving using the proposed algorithm is outlined. To demonstrate the feasibility of design, a detailed electromagnetic analysis, stator thermal analysis with a jet impingement design, and magnet demagnetization risk analysis were also presented. Full article

Listening to music is a well-established strategy to enhance exercise capacity, yet the specific mechanisms linking music choice to performance enhancement remain fragmented. This scoping review systematically summarizes the existing literature on the effects of music choice (i.e., self-selected, preferred music) on performance and psychophysiological determinants of exercise capacity to establish an updated rationale for the use of personalized music interventions in training. Following PRISMA-ScR guidelines, a systematic search of five databases (PubMed, Web of Science, Embase, Scopus, CINAHL) was performed for studies published between January 2000 and April 2025. Peer-reviewed articles investigating the ergogenic effects of self-selected or preferred music with psychophysiological outcomes were included. Thirty-two studies met inclusion criteria. Overall, evidence supports consistent performance enhancement from choice music (CM) across modes of exercise including aerobic endurance, anaerobic power, and muscular endurance activities while maximal strength was largely unaffected. The most robust and consistent mechanisms underpinning the benefits of CM during exercise were psychological in nature, including improvements in affect, arousal, motivation, and perception of exertion. Notable physiologic benefits were also identified, including altered cortical excitability, autonomic modulation, and improvements in neuromuscular efficiency. Herein, this review provides a psychophysiological framework whereby CM acts as a primary mediator to induce psychological and physiological cascades which synergistically contribute to ergogenic benefits. Evidence heavily supports the superiority of CM to improve exercise performance across various modalities. Full article

Background: The back squat is a key strength and conditioning exercise used to develop lower-limb strength and power, yet little is known about how movement velocity influences its acute performance-enhancing effects, such as improvements in countermovement jump height and power. The present study examined the acute effects of slow (v_slow) versus fast (v_fast) eccentric-phase velocity during back squats performed withmaximal concentric velocity on subsequent countermovement jump (CMJ) performance, using a randomized, crossover design. Methods: Fourteen male subjects (age = 22.9 ± 1.9 years; height = 1.8 ± 0.1 m; mass = 76.4 ± 8.3 kg) visited the laboratory on two separate days and completed a comprehensive task-specific warm-up followed by three v_slow or v_fast back squats at 70% of one-repetition maximum. Three CMJs were performed before and 30 s, 4 min, 8 min, and 12 min after the interventions. Jump height, peak power, kinetic energy, maximum knee angle, and knee angular velocities in both eccentric (downward) and concentric (upward) phases were recorded. Results: No significant (p > 0.05) between-condition differences were detected in any measure. Compared to pre-intervention, significant increases (collapsed data) were detected in jump height (6.0%; d = 0.68–0.83), power (3.6–6%; r = 0.32–0.38), and kinetic energy (5.0–8.0%; d = 0.62–0.86) at 30 s and 4 min. Conclusions: Given the lack of between-condition differences, the eccentric movement velocity of moderate conditioning back squats with maximal concentric velocity exercises does not appear to influence subsequent jump performance enhancements. Thus, either conditioning activity can be used to improve subsequent jump performance. However, as performance was enhanced only at 30 s and 4 min post-intervention, the window of opportunity is narrow, and timing should be carefully considered when including such activities in pre-competition routines. Full article

The transition towards sustainable energy systems is critically dependent on the reliable integration of renewable energy sources into the power grid. With the increasing penetration of renewable generation, hybrid grid-connected systems comprising grid-following (GFL) and grid-forming (GFM) converters have become essential in modern power stations. This paper addresses a key challenge to sustainable grid operation: maintaining stability and power delivery during grid faults. When faults cause voltage sags at the point of common coupling (PCC), different low-voltage ride-through (LVRT) strategies significantly impact both the voltage support capability and the active power transmission capacity, which are vital for a stable and resilient energy supply. To address this, the paper proposes a coordinated LVRT strategy for GFL/GFM converters that adapts to varying grid requirements, thereby promoting sustainable grid integration. First, the topology and control strategies of the hybrid system are briefly described. The conventional LVRT control strategies for both GFL and GFM converters are then improved. Based on the severity of the grid voltage sag, the converters’ active and reactive power output are adaptively adjusted. This dual-function approach not only effectively limits fault currents, protecting sensitive equipment, but also prioritizes the continuous transmission of active power, thereby minimizing the loss of renewable generation during faults and supporting grid stability. Subsequently, through an analysis of the voltage and active power characteristics of different LVRT modes, a coordinated strategy is designed. Unlike single-converter LVRT control, the proposed method flexibly selects and adjusts control modes to meet specific grid code requirements, ensuring robust voltage support and maximizing the utilization of clean energy even under adverse conditions. Finally, the effectiveness of this coordinated control strategy in ensuring a sustainable and resilient grid connection is validated through MATLAB R2022b/Simulink simulations. Full article

The inherent bottleneck of the von Neumann architecture and the limited power budget of edge devices necessitate energy-efficient hardware solutions for artificial intelligence. Memristor-based In-Memory Computing (IMC) has emerged as a promising candidate; however, the high-power consumption of peripheral circuits, particularly Analog-to-Digital Converters (ADCs), and the reliability issues of memristive devices remain significant challenges. In this paper, we propose a hybrid Convolutional Spiking Neural Network (CSNN) architecture designed for resource-constrained edge computing. Our approach integrates digital Non-Leaky Integrate-and-Fire (NLIF) neurons with Knowm Self-Directed Channel (SDC) memristor-based synapses in a 1T1R crossbar array. To maximize power efficiency, we replace conventional high-resolution ADCs with a streamlined readout circuit utilizing a Current Sense Amplifier (CSA) and a 1-bit comparator. Furthermore, we employ an intensity-to-latency temporal coding scheme to minimize spike activity and mitigate device endurance degradation. We validated the proposed system using the MNIST dataset, achieving a classification accuracy of 97.8%, which is comparable to state-of-the-art floating-point SNNs using supervised learning methods. Power analysis confirms that our 1-bit readout method consumes only 18.4% of the energy required by an 8-bit ADC-based approach while maintaining negligible accuracy loss. Additionally, the deterministic single-spike nature of our temporal coding significantly reduces write stress on memristors compared to rate coding. These results demonstrate that the proposed hybrid CSNN offers a robust and energy-efficient solution for neuromorphic edge intelligence. Full article

The sustainable valorization of citrus processing by-products represents a key challenge for the food industry, aiming to reduce waste while recovering valuable bioactive compounds. In this study, a cloud point extraction strategy was developed using soy lecithin as a natural, food-grade surfactant to isolate phenolic antioxidants from orange juice industry residues. Response Surface Methodology was applied to two streams of orange juice by-products, to evaluate the combined effects of pH, NaCl concentration, and lecithin content on extraction efficiency, with total polyphenolic content, DPPH radical scavenging activity, and ferric reducing antioxidant power serving as response variables. Partial Least Squares (PLS) analysis was additionally employed to integrate all antioxidant responses and identify a multivariate optimum. The optimized conditions (pH 3.4, 12% NaCl, 11% lecithin) enabled maximal recovery of antioxidant constituents, highlighting the effectiveness of lecithin-based micellar systems. To assess practical applicability, the optimized extract from the oil emulsion residue (Stream A) was incorporated into tsipouro, a traditional Greek distillate, and its stability was monitored under controlled light and temperature conditions for 30 days at three concentration levels. Results demonstrated that both environmental factors significantly influenced antioxidant retention and physical stability, underscoring the importance of formulation design. Specifically, high gel concentration at 2% w/v, low temperature at 20 °C and light exposure provided the highest overall desirability for TPC, FRAP, and DPPH responses. Overall, this work introduces a green, scalable, and food-compatible extraction approach that not only supports circular economy principles but also opens new opportunities for the development of functional alcoholic beverages enriched with natural antioxidants. Full article

Stem cell heterogeneity represents a critical yet underexplored variable in laser-assisted regenerative strategies. While photobiomodulation has been shown to influence mesenchymal stem cell (MSC) behavior, it remains unclear whether stem cell maturation status modulates responsiveness to Er,Cr:YSGG irradiation. This study investigated the differential response of magnetically separated STRO-1⁺ and STRO-1⁻ SHED subpopulations to low-power Er,Cr:YSGG laser stimulation (0.10 W and 0.25 W), focusing on viability, extracellular matrix production, and lineage commitment. STRO-1⁺ cells comprised 13.4% ± 1.2% of the total Stem Cells from Human Exfoliated Deciduous teeth (SHED) population. Laser exposure did not impair metabolic activity in either subpopulation. Collagen synthesis demonstrated a power- and time-dependent increase, with maximal enhancement observed in STRO-1⁺ cells at 0.25 W after 7 days. Laser irradiation selectively promoted osteogenic differentiation, as evidenced by increased alkaline phosphatase (ALP) expression at 0.10 W and enhanced mineral deposition, while chondrogenic potential remained unaffected and adipogenesis was reduced following 0.10 W exposure. These findings suggest that ALP expression is temporally and power-dependently modulated during osteogenic progression. Overall, Er,Cr:YSGG photobiomodulation does not uniformly affect heterogeneous SHED populations but modulates lineage allocation and extracellular matrix deposition in a maturation- and power-dependent manner. Integrating stem cell subpopulation selection with laser-based bioactivation may represent a strategy to refine regenerative endodontic and biomaterial-guided therapies. Full article

Reconfigurable intelligent surfaces (RISs) hold promising technical prospects for 6G wireless communications to enhance system capacity, coverage and sum-rate. Unlike existing studies deploying only passive or active RISs, this paper adopts a novel hybrid RIS architecture that optimally allocates the number of active and passive elements. Under fixed quantities of both RIS element types in the fixed hybrid RIS, it simultaneously increases the number of base station antennas and served users, focusing on solving rate optimization for hybrid RIS-assisted MISO systems deployed in various scenarios. This paper establishes a fundamental model for hybrid RIS reflection signals. To better characterize the performance of the proposed hybrid RIS architecture, an optimization problem is formulated to maximize the sum-rate of the hybrid RIS-assisted multi-user, multiple-input, single-output (MU-MISO) system. An efficient algorithm is proposed combining fractional programming (FP), alternating optimization, and Lagrange duality transformation. Simulation results demonstrate that with hybrid RIS assistance, the system’s sum-rate gain increases by 49.1% and 40%, respectively, compared to systems with only active RIS deployment. This achieves higher sum-rate gains at lower power consumption. Full article

Objective: We examined vastus lateralis (VL), gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and biceps femoris (BF) muscle architecture and force–time parameters recorded during a countermovement jump (CMJ). Methods: Eighty-nine 9 year-old girls (43 rhythmic gymnasts and 46 recreationally active controls) were assessed in: (a) muscle architecture (fascicle length—FL; angle; muscle thickness; and anatomical cross-sectional area—CSA) using ultrasonography, (b) CMJ performance (maximum force—Fmax; rate of force development—RFD; jump height; and peak power) using force–time data, and (c) anthropometrics and body composition. Results: Rhythmic gymnasts exhibited greater BF fascicle length and muscle thickness than controls (7.84 ± 0.73 vs. 7.26 ± 0.75 cm and 1.76 ± 0.19 vs. 1.61 ± 0.22 cm, respectively, p < 0.001), while VL muscle CSA was larger in controls (p = 0.001). When normalized to the respective segment length (thigh or shank), the FL was longer in gymnasts across all muscles (p ≤ 0.017). Gymnasts also demonstrated greater CMJ height (13.1%, p = 0.005), power scaled to body mass, and RFD (p < 0.005), while controls produced a greater Fmax (16.9%, p = 0.002). Body mass was the strongest predictor of Fmax in both groups (p < 0.001). CMJ power was best predicted by gastrocnemius CSA in gymnasts and by VL CSA combined with maturity offset in controls (all p < 0.001). Maturity offset and gastrocnemius CSA also predicted allometrically scaled power in controls. Conclusions: Rhythmic gymnasts are characterized by muscle-specific adaptations, specifically in the BF muscle FL and muscle thickness, which favor superior CMJ performance. In developing athletes, body mass is primarily related to maximal force, whereas muscle CSA is more closely associated with power output. Full article

This study evaluated the effect of freezing and frozen storage at three temperatures (−20, −30, −40 °C) on hop (Humulus lupulus L.) secondary metabolites and antioxidant capacity. These temperatures were selected based on the glass transition temperature (T_g’) of the maximally freeze-concentrated matrix. Cones were analyzed after freezing (t₀) and up to 360 days (t₃₆₀) by high-performance liquid chromatography with ultraviolet diode-array detection (HPLC-UV/DAD) for bitter acids, prenylflavonoids and phenolic acids, and by the Folin–Ciocalteu, ABTS the radical cation scavenging assay (ABTS) and the ferric-reducing antioxidant power assay (FRAP) assays for total phenolic content and antioxidant activity. Confocal laser scanning microscopy (CLSM) at t₃₆₀ was used to relate microstructural damage to metabolite retention. Freezing at −40 °C ensured the highest retention of bitter acids, phenolic acids (gallic, syringic, vanillic, caffeic, chlorogenic), and antioxidant capacity, whereas xanthohumol and 8-prenylnaringenin reached their maximum levels at −30 and −20 °C, respectively. During frozen storage, changes in metabolite profiles were mainly driven by storage time rather than temperature; over 360 days, α-acids, colupulone, xanthohumol and selected phenolic acids increased, while most other compounds declined. Multivariate analysis and CLSM elucidated the relationships between process conditions, tissue structure and metabolite profiles, enabling the selection of freezing and storage temperatures to optimally preserve different targets of hop bioactives and overall indicating −40 °C as the most effective. Full article

Cordyceps militaris is an entomopathogenic fungus traditionally used in Asian ethnomedicine and increasingly investigated for its potential health-promoting properties, including immunomodulatory and anti-inflammatory activities. In recent years, it has gained attention as a dietary supplement with possible applications in sports nutrition. This narrative review summarizes and critically evaluates the current human evidence regarding the ergogenic and post-exercise recovery effects of C. militaris supplementation in healthy individuals. A structured database search was conducted using predefined eligibility criteria, and the methodological quality of included studies was appraised through domain-based risk-of-bias assessment. Five intervention studies published between 2017 and 2024, comprising 321 participants aged 16–35 years, were identified. Supplementation protocols ranged from 1 to 16 weeks, with daily doses of 1–12 g administered either as isolated fungal material or as a part of multi-ingredient formulations. Assessed outcomes included indices of aerobic performance and exercise capacity, such as maximal or peak oxygen uptake (VO₂max/VO₂peak), time to exhaustion, power output, running performance, and maintenance of peripheral oxygen saturation during high-intensity exercise. Several studies also evaluated biochemical markers related to muscle damage and inflammatory responses, including creatine kinase, blood urea nitrogen, and white blood cell counts. Although some studies reported improvements in selected performance and recovery parameters, the findings were inconsistent. The certainty of the evidence is limited by small sample sizes, heterogeneity of participants and exercise protocols, insufficient reporting of randomization, lack of trial registration in most studies, absence of standardized preparations with quantified bioactive constituents, and the use of multi-ingredient supplements. Well-designed randomized controlled trials using chemically characterized preparations and homogeneous athletic populations are required to clarify the efficacy and practical relevance of C. militaris in sports nutrition. Full article

This systematic review focuses on the effect of concurrent high-intensity interval training (HIIT) and resistance training on musculoskeletal function in adult individuals. Four electronic databases (PubMed, Web of Science Core Collection, Scopus, and PsycINFO) were searched for controlled trials in older or middle-aged adults, in recreationally exercising adults, and in athletic or tactical populations, which completed parallel HIIT and resistance training and described musculoskeletal responses to the intervention up to 30 November 2025. A total of 18 trials fulfilled the eligibility criterion and were synthesized narratively across the domains of maximal strength, explosive performance, neuromuscular activity, muscle morphology and architecture, tendon-related outcomes, and adherence and safety. Most 8- to 12-week interventions maintained two to three weekly resistance sessions and were designed in time-effective HIIT formats, increasing or preserving maximal strength in older subjects as well as younger ones that were trained. Explosive performance metrics, including both jump and sprint tasks, were usually preserved or even improved by the maintenance of the power-oriented component in resistance-based exercise sessions. The limited electromyography data indicated improved neuromuscular activation during submaximal tasks, particularly in older subjects, whereas some studies reported subtle increases or maintenance of muscle size and selective architectural patterns during application of progressive loading. Tendon-specific adaptations are difficult to measure, as imaging was seldom available, but functional tasks influenced by the muscle–tendon unit have been studied in multiple studies. Adherence was good, and adverse events were rare in all studies. Overall, the evidence suggests that well-designed concurrent HIIT and resistance training programs can improve or maintain musculoskeletal performance, although the magnitude and expression of these adaptations vary according to population characteristics and intervention design. Importantly, by integrating neuromuscular, morphological, and performance-related outcomes across diverse adult populations, this review provides a musculoskeletal-centered synthesis that extends prior concurrent training reviews beyond cardiorespiratory or interference-focused perspectives. Full article

Abscess formation is commonly precipitated by bacterial infection. This study delineates the phytochemical composition and evaluates the antioxidant, antibacterial, and anti-biofilm activities of a Thai traditional anti-abscess herbal formulation comprising Curcuma zedoaria, Vitex trifolia, and Azadirachta indica. Validated high-performance liquid chromatography–photodiode array detection (HPLC–PDA) analysis of the ethanolic extract identified curcumin, demethoxycurcumin, bisdemethoxycurcumin, and vitexicarpin as principal constituents. Total phenolic and flavonoid contents were 32.08 ± 2.54 mg GAE/g and 17.52 ± 1.28 mg QE/g dry weight, respectively. Antioxidant assessment by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay yielded an half maximal inhibitory concentration (IC₅₀) of 53.46 ± 3.24 µg/mL, while reducing power corresponded to 383.97 ± 13.24 µg FeSO4/g dry weight. Molecular orbital analysis revealed a highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) gap for vitexicarpin (ΔE = 9.7710 eV), indicative of greater radical-scavenging potential relative to curcuminoids. Antibacterial assays demonstrated selective activity against Staphylococcus epidermidis (inhibition zone 1.48 ± 0.16 cm), with no observed inhibition of Staphylococcus aureus or Streptococcus pyogenes. Curcumin exhibited the highest activity against S. epidermidis (minimum inhibitory concentration (MIC) 62.5 µg/mL; minimal bactericidal concentration minimal bactericidal concentration (MBC) 125 µg/mL). Molecular docking showed curcumin binding to the teicoplanin-associated transcriptional regulator (TcaR) with a binding energy of −8.00 kcal/mol, comparable to methicillin (−8.16 kcal/mol), suggesting a potential mechanism for modulation of biofilm-associated regulatory pathways. Collectively, these findings indicate that the formulation has measurable antioxidant activity and targeted antibacterial efficacy against S. epidermidis, which may contribute to attenuation of abscess progression via interference with biofilm regulation. Full article