Search Results (1,992)

Background: Neuromuscular electrical stimulation (NMES) is an effective exogenous neuromuscular activation method widely used in sports training and rehabilitation. However, existing research primarily focuses on land-based sports or single-joint movements, with limited in-depth exploration of its intervention effects and underlying neuromuscular control mechanisms for complex, multi-joint coordinated aquatic activities like breaststroke swimming. This study aimed to investigate the effects of NMES combined with traditional resistance training on neuromuscular function during sport-specific technical movements in breaststroke athletes. Methods: A randomized controlled trial was conducted with 30 national-level or above breaststroke athletes assigned to either an experimental group (NMES combined with traditional squat resistance training) or a control group (traditional squat resistance training only) for an 8-week intervention. A specialized fully waterproof wireless electromyography (EMG) sensor system (Mini Wave Infinity Waterproof) was used to synchronously collect surface EMG signals from 10 lower limb and trunk muscles during actual swimming, combined with high-speed video for movement phase segmentation. Changes in lower limb explosive power were assessed using a force plate. Non-negative matrix factorization (NMF) muscle synergy analysis was employed to compare changes in muscle activation levels (iEMG, RMS) and synergy patterns (spatial structure, temporal activation coefficients) across different phases of the breaststroke kick before and after the intervention. Results: Compared to the control group, the experimental group demonstrated significantly greater improvements in single-leg jump height (Δ = 0.06 m vs. 0.03 m) and double-leg jump height (Δ = 0.07 m vs. 0.03 m). Time-domain EMG analysis revealed that the experimental group showed more significant increases in iEMG values for the adductor longus, adductor magnus, and gastrocnemius lateralis during the leg-retraction and leg-flipping phases (p < 0.05). During the pedal-clamp phase, the experimental group exhibited significantly reduced activation of the tibialis anterior alongside enhanced activation of the gastrocnemius. Muscle synergy analysis indicated that post-intervention, the experimental group showed a significant increase in the weighting of the vastus medialis and biceps femoris within synergy module 4 (SYN4, related to propulsion and posture) (p < 0.05), a significant increase in rectus abdominis weighting within synergy module 3 (SYN3, p = 0.033), and a significant shortening of the activation duration of synergy module 2 (SYN2, p = 0.007). Conclusions: NMES combined with traditional resistance training significantly enhances land-based explosive power in breaststroke athletes and specifically optimizes neuromuscular control strategies during the underwater breaststroke kick. This optimization is characterized by improved activation efficiency of key muscle groups, more economical coordination of antagonist muscles, and adaptive remodeling of inter-muscle synergy patterns in specific movement phases. This study provides novel evidence supporting the application of NMES in swimming-specific strength training, spanning from macroscopic performance to microscopic neural control. Full article

Hydraulic manipulators are vital for heavy-duty applications such as rescue robotics due to their high power density, yet these scenarios increasingly demand safe and compliant physical interaction. Impedance control is a key enabling technology for such capabilities. However, a significant challenge arises when implementing impedance control on Independent Metering Systems (IMS), which are widely adopted for their energy efficiency. The inherent multi-mode operation of IMS relies on discrete switching logic. Crucially, when mode switching occurs during physical interaction with the environment, the unpredictable external forces can trigger frequent and abrupt switching between operating modes (e.g., resistive and overrunning), leading to severe chattering. This phenomenon not only undermines the smooth interaction that impedance control aims to achieve but also jeopardizes overall system stability. To address this critical issue, this paper proposes a seamless control framework based on a Takagi–Sugeno (T-S) fuzzy model. Two premise variables based on the physical characteristics of the system are innovatively designed to make the rule division highly consistent with the dynamic nature of the system. Asymmetric membership functions are introduced to handle direction-dependent switching, with orthogonal functions ensuring logical exclusivity between extension and retraction, and smooth complementary functions enabling seamless transitions between resistance and overrunning modes. Experimental validation on a small hydraulic manipulator validates the effectiveness of the proposed method. The controller eliminates switching-induced instability and smooths velocity transitions, even under dynamic external force disturbances. This work provides a crucial solution for high-performance, stable hydraulic interaction control, paving the way for the application of hydraulic robots in complex and dynamic environments. Full article

Background: Transorbital approaches (TOAs) provide minimally invasive access to anterior and middle cranial fossa lesions. However, orbital retraction remains a challenge, as narrow corridors limit maneuverability and excessive retraction increase complication risk. Conventional rigid or malleable retractors may obstruct the corridor or exert uneven pressure on delicate tissues. We present a handmade, semi-rigid plastic retractor as a low-cost, effective solution to optimize orbital retraction in TOAs. Methods: The retractor was fashioned from a cylindrical plastic drill bit container, cut into two semicircular pieces with rounded edges. Its application is described within the transorbital eyebrow lacrimal keyhole approach (TELKA). During the bony phase, one piece is placed on the orbital roof for periorbital retraction and protection, while a second may be positioned laterally to protect the temporalis muscle when required. Once adequate working space is achieved, the lateral retractor is removed and the medial one maintained throughout the procedure. Technical details are illustrated through representative clinical cases, supported by anatomical dissection and an operative video. Results: Across thirteen TELKA procedures, the semi-rigid retractor provided stable, low-intensity retraction with even pressure distribution, minimizing corridor obstruction and facilitating both microscopic and endoscopic maneuverability. No orbital or visual complications related to retraction were observed; periorbital structures were preserved, with no postoperative proptosis or aesthetic defects. Conclusions: This handmade, semi-rigid retractor is a safe, customizable, and reproducible tool that enhances surgical freedom while minimizing orbital morbidity in TOAs. It is particularly advantageous in keyhole procedures such as TELKA, representing a promising alternative to conventional retraction systems. Full article

Amphibious light sport aircraft (LSA) combine the versatility of land and water operations but suffer aerodynamic penalties from their inherent design requirements, limiting cruise performance. This study investigates two drag reduction features for a proposed high-performance amphibious LSA developed by Altavia Aerospace. The concept targets a cruise speed of 140 KTAS, using retractable wingtip pontoons and a novel retractable hull step fairing. A 1/5-scale flying model was built and flight tested to assess the aerodynamic benefits of these features and evaluate sub-scale flight testing as a tool for drag measurement. Estimated propulsive power and GPS-based speed data corrected for wind were used to compute an estimated 17% reduction in drag coefficient by retracting the pontoons. The hull step fairing showed no measurable gains, likely due to inconsistent battery voltage, despite literature indicating potential 5% drag savings. Drag measurement precision of 7–9% was achieved using the power-based method, with potential precision better than 3% achievable if the designed thrust data system were fully validated and an autopilot integrated. A performance estimation for Altavia Aerospace’s concept predicts a cruise speed of 134 KTAS at 10,000 ft. Achieving the target of 140 KTAS may require further aerodynamic refinement, with investigation of a tandem seating configuration to reduce frontal area recommended. The study provides an initial drag assessment of retractable wingtip pontoons and demonstrates the potential of sub-scale flight testing for comparative drag analysis—two novel contributions to the field. Full article

The Chinese plum (Prunus salicina L.), ‘Zuili’, is a geographically protected cultivar that is valued for its high polyphenol levels and distinctive flavor. Light availability strongly influences sugar accumulation and secondary metabolism in plum fruit, yet the molecular processes associated with quality variation under protected cultivation remain unclear. Here, we compare three cultivation systems—multi-span greenhouse (M), retractable electric rain shelter (R), and conventional open field (CK)—to evaluate their effect on fruit quality using integrated transcriptomic and metabolomic analyses. Field trials showed that M treatment increased fruit sweetness by 28.10% versus CK (14.68 vs. 11.46 °Brix, p < 0.001) without yield loss and significantly improved vertical fruit diameter. RNA-seq analysis identified 7561 and 7962 upregulated genes in the M and R treatments compared to CK, respectively, with significant functional enrichment in pathways related to sucrose metabolism, light-response, and ethylene-mediated signaling. Untargeted metabolomic signaling identified 1373 metabolites, with shading treatments increasing the abundance of several sugar-conjugated compounds (e.g., epicatechin 3-O-(2-trans-cinnamoyl)-β-D-allopyranoside). Multi-omics integration revealed coordinated changes in gene expression and metabolite abundance, suggesting that controlled light environments are associated with the concurrent modulation of sugar metabolism and phenylpropanoid-related pathways. These patterns were supported by the upregulation of GT2-family glycosyltransferase genes and the accumulation of lignin-related flavonoid precursors, such as pinobanksin and pinobanksinol. Collectively, these results highlight statistically robust associations between light-regulated cultivation practices and fruit quality traits, providing a molecular framework for optimizing protected cultivation strategies to enhance both the sensory and nutritional attributes of P. salicina fruit without compromising yield. Full article

Background/Objectives: Down Syndrome (DS) is frequently associated with oral-motor dysmorphologies, like oral hypotonia, tongue protrusion, short palate, and malocclusion, compromising the oral functions of sucking, chewing, swallowing, and speech production. Therapeutic interventions with stimulating palatal plates (SPP) have been proposed to prevent and improve oral-motor dysmorphologies in DS. This study proposes a new digital workflow for the manufacturing and use of a modified SPP. Methods: We report the application of the new workflow to five clinical cases, all infants with DS showing oral-motor disorders, aged between 5 and 11 months. The workflow is described step-by-step, from the mouth scanning protocol and model printing to SPP manufacturing and delivering, and assessment of oral-morphological features and language abilities via video captures and parental questionnaires. Key novel features include an SPP with an acrylic extension with a pacifier terminal and, importantly, the use of an infant-friendly intraoral scanner. Results: The new workflow had good acceptability by infants and parents, offering a safe, easy-to-implement, and feasible solution for SPP design, as it avoided the high risks associated with impression materials. It also supported the use of the SPP to promote tongue stimulation, retraction, and overall oral-muscle function in oral-motor disorders in children with DS, especially in infants. Conclusions: Within the limitations of the current study, it was shown that the proposed digital workflow constitutes a viable and infant-friendly approach to the production and use of a modified SPP, and thus promises to contribute to improving oral morphology and auditory-motor language abilities. Full article

This study investigates the influence mechanism of key factors on the heating value of syngas during underground coal gasification (UCG) and proposes an optimization path for enhanced energy conversion efficiency based on typical global field test data. Integrating data review and pattern analysis, it systematically explores the influence of core factors, including coal seam characteristics, reactor structure, and gasification agent ratio. It is found that the relationship between syngas heating value and coal rank is not simply linear, with representative heating values ranging from 4.13 to 11.96 MJ/m³. Medium-rank coal, characterized by “medium volatile matter and low ash content”, yields high-heating-value syngas when paired with air/steam as the gasification agent. Shaftless reactor structures demonstrate superior overall performance compared to shaft-based designs, with the representative heating value improving from 3.83 MJ/m³ to 7.8 MJ/m³. The combination of U-shaped horizontal wells with the Controlled Retracting Injection Point (CRIP) technology improves the heating value. Effective control over the syngas heating value can be achieved by optimized composition and ratio of the gasification agent, with representative value of 9.10 MJ/m³ in oxygen-enriched steam gasification compared to 4.28 MJ/m³ in air gasification. Based on an evaluation of data fluctuation characteristics, the significance ranking of the factors is as follows: gasification agent, coal rank, and reactor structure. Consequently, an engineering optimization path for enhancing UCG syngas heating value is proposed: prioritize optimizing the composition and ratio of the gasification agent as the primary means of heating value control; on this basis, rationally select coal rank resources, focusing on process compatibility to mitigate performance fluctuations; and then incorporate advanced reactor structures to construct a synergistic and efficient gasification system. This research can provide theoretical support and data references for engineering site selection, process design, and operational control of UCG projects. Full article