Search Results (57)

The hub drive system has emerged as a promising development orientation for future vehicles, with the planetary gear reducer serving as its key power transmission component. Considering the complexity of the reducer’s dynamic characteristics under high-torque conditions, this study establishes a lumped parameter translational–torsional coupling dynamic model for the two-stage planetary gear reducer based on Lagrange’s dynamic equations, incorporating critical nonlinear factors such as time-varying meshing stiffness and tooth clearance. No-load vibration tests were conducted to collect vibration acceleration of the secondary planet carrier and the primary ring gear under the operating condition of the primary sun gear rotating at 606 r/min. Experimental verification indicates that the errors between the simulation results and experimental acceleration amplitudes are 9.09% and 14.63%, respectively, confirming the validity and reliability of the theory model. This translational–torsional coupling dynamic model provides significant theoretical support for the dynamic optimization design, vibration control, and performance improvement of reducers in high-torque hub drive systems. Full article

Cardiovascular disease (CVD) remains a leading cause of global morbidity and mortality, and its initiation and progression are closely associated with multiple molecular mechanisms. Neutrophil extracellular traps (NETs) are mesh-like structures composed of DNA, histones, and antimicrobial proteins that are released by neutrophils during inflammation or infection. They play a crucial role in innate immune defense. However, when the dynamic balance of NETs is disrupted by excessive formation, persistent accumulation, or impaired clearance, NETs are no longer merely bystanders. Instead, they actively drive pathological processes in multiple CVDs and serve as a critical link between inflammation and cardiovascular injury. Given the central role of NETs in CVD pathogenesis, including atherosclerosis, myocardial ischemia–reperfusion injury, pulmonary arterial hypertension, atrial fibrillation, and heart failure, therapeutic strategies targeting NETs, such as inhibiting aberrant formation, enhancing clearance, or neutralizing toxic components, have emerged as promising approaches. In recent years, traditional Chinese medicine (TCM) and natural products have shown potential therapeutic value by modulating NET formation and promoting NET degradation, owing to their multitarget, multipathway regulatory effects. This article reviews the mechanisms by which NETs operate in CVDs and explores potential pathways through which TCM and natural active ingredients prevent and treat CVDs by regulating NETs. This review provides theoretical support for further research and clinical application. Full article

The steering linkage represents a key subsystem of any automobile, playing a direct role in vehicle handling, driving safety, and overall comfort. Within this mechanism, the tie rod and tie rod end are crucial for transmitting steering forces from the gear to the wheel hub. A typical issue that gradually develops in these components is the clearance appearing in the spherical joint, caused by wear, corrosion, and repeated operational stresses. Even small clearances can noticeably reduce stiffness and natural frequencies, making the system more sensitive to vibration and premature failure. In this work, the effect of spherical joint clearance on the dynamic behavior of the tie rod-tie rod end assembly was analyzed through numerical simulation combined with experimental observation. Three-dimensional CAD models were meshed with tetrahedral elements and subjected to modal analysis under several clearance conditions, while boundary constraints were set to replicate real operating conditions. Experimental measurements on a dedicated test rig were used to assess joint clearance and wear in service parts. The results indicate a strong nonlinear relationship between clearance magnitude and modal response, with PTFE bushing degradation identified as the main source of clearance. These findings link the evolution of clearance to the change in vibration characteristics, providing useful insight for diagnostic approaches and predictive maintenance aimed at improving steering reliability and vehicle safety. Full article

In certain mining areas, bauxite ore exhibits high and uneven hardness, causing frequent overloads in the cutting heads of bauxite mining equipment and challenging the dynamic performance and reliability of its gear transmission system. To investigate the influence of macro-geometric parameters, a dynamic model was built using MASTA software (version 13.0.1). This study systematically analyzed the effects of pressure angle, face width, and bottom clearance coefficient on gear meshing characteristics, service life, and vibration noise under various loads. A preferred set of parameters was determined and validated through vibration and noise tests. The results show that increasing the pressure angle and face width improves gear meshing and fatigue life, while the bottom clearance coefficient has an optimal value of 0.4. Increasing the bottom clearance coefficient exacerbates vibration and noise, with other parameters causing fluctuations under different conditions. The optimal parameters of 23° pressure angle, 75 mm face width, and 0.4 bottom clearance coefficient effectively reduce vibration and noise, providing a theoretical and practical basis for improving the cutting transmission system. Full article

Background/Objectives: The global aging population faces rising rates of cognitive decline and neurodegenerative disorders. This review explores how physical exercise influences brain health in aging, focusing on mechanisms, moderators, and personalized strategies to enhance cognitive resilience. Methods: A narrative review methodology was applied. Literature published between 2015 and 2025 was retrieved from PubMed, Scopus, and Web of Science using keywords and MeSH terms related to exercise, cognition, neuroplasticity, aging, and dementia. Inclusion criteria targeted peer-reviewed original studies in humans aged ≥60 years or aged animal models, examining exercise-induced cognitive or neurobiological outcomes. Results: Evidence shows that regular physical activity improves executive function, memory, and processing speed in older adults, including those with mild impairment or genetic risk (e.g., APOE ε4). Exercise promotes neuroplasticity through increased levels of BDNF, IGF-1, and irisin, and enhances brain structure and functional connectivity. It also improves glymphatic clearance and modulates inflammation and circadian rhythms. Myokines act as messengers between muscle and brain, mediating many of these effects. Cognitive benefits vary with exercise type, intensity, and individual factors such as age, sex, chronotype, and baseline fitness. Combined interventions—physical, cognitive, nutritional—show synergistic outcomes. Digital tools (e.g., tele-exercise, gamification) offer scalable ways to sustain engagement and cognitive function. Conclusions: Physical exercise is a key non-pharmacological strategy to support cognitive health in aging. It acts through diverse systemic, molecular, and neurofunctional pathways. Tailored exercise programs, informed by individual profiles and emerging technologies, hold promise for delaying or preventing cognitive decline. Full article

Carbon fiber-reinforced polymer (CFRP) composite–metal joint structures are susceptible to localized discharge and thermal damage under lightning current, posing serious safety concerns for critical aircraft components such as fuel tanks. In this study, we investigated the conductive behavior of composite–metal lap joint structures subjected to multiple continuous lightning current components (A, B, and C*) through a combination of experimental testing and numerical simulations. The effects of fastener assembly methods on ignition events were systematically examined, and the ignition source generation mechanisms under interference-fit and clearance-fit conditions were revealed. The protective performance of different assembly approaches against ignition sources was also evaluated. The results indicate that the assembly type and installation method have a pronounced influence on the ignition threshold and damage modes. Specifically, interference-fit joints with wet installation exhibited no ignition even at a current of 91 kA, whereas clearance-fit joints without wet installation generated potential ignition sources at 14 kA. Wet installation effectively increased the ignition threshold by approximately twofold. Copper mesh on the composite surface played a crucial role in current conduction. The simulation results further demonstrated that the current became concentrated at the composite–metal interface upon removal of the copper mesh, causing local temperatures to exceed the resin pyrolysis temperature (893 K), thereby creating potential ignition sites. This study enhances the understanding of lightning ignition mechanisms in composite–metal lap joint structures and provides both theoretical and experimental foundations for improving lightning protection design in aircraft fuel tank structures. Full article

Mesozooplankton (netplankton > 250 µm) were sampled during nine cruises over one year at three stations in the Shannon estuary system, Ireland. A net with three mesh sizes was used to capture a wider range of plankton sizes than a standard single-mesh net. An innovation was the incorporation factorial analysis of celestial (seasonal) variables, spring equinox (Spr) and summer solstice (Sum), together with physicochemical and biological variables, without presuming cause or effect. Over the year, water temperature and salinity were closely positively related to each other and to the occurrence of most of the taxa. The approximate trophic impact of by major taxa was estimated from abundance and published clearance rates. Overall, the mean herbivorous/detritivorous grazing by mesozooplankton was 54 L m⁻³ d⁻¹. Among the mesozooplankters and mysids, Mesopodopsis slabberi (predominantly April–November) contributed 96.3% and the appendicularian Oikopleura dioica (May–October) contributed 2.0% (nano- and picoplankton), while copepods only provided 0.98%. The ctenophore Pleurobrachia pileus (present April–October) grazed 2.0% (carnivorous grazing mysids and copepods contributed additional unquantified carnivorous grazing). These data, collected 45 years ago, provide a valuable baseline for assessing subsequent ecological changes. Full article

Background/Objectives: Introducing new transformative surgical technology involves navigating a complex process from design to implementation, often hindered by various barriers that delay the transition into clinical practice. This review critically examines the barriers, proposes a unified guide for medical device implementation in the Australian healthcare system utilising the validated Medtech Innovation Guide, and compares regulatory frameworks in Australia, the United Kingdom, and the United States of America. Methods: We conducted a literature review using MEDLINE and EMBASE with MeSH terms or emtree terms and keywords “new OR novel” AND “surgical device OR medical device OR health technology OR surgical technology OR surgical instrument OR transformative technology OR technological innovation OR technological change” AND “implementation OR adoption OR innovation adoption” AND “surgery OR surgical” AND “Australia”. We also assessed governmental websites (gov.au) and documents as well as the Royal Australasian College of Surgeons (RACS) website, policies, and position statements. Furthermore, Australian medical technology start-up companies were asked for any published roadmaps. Results: Four key stakeholder groups were identified: medical professionals, government, hospitals, and patients/consumers. Barriers include surgeon scepticism, regulatory hurdles (e.g., Australian Register of Therapeutic Goods), hospital clearance processes, and meeting patient expectations. To address these challenges, we propose a five-phase system: surgical device development (phase one), compliance with regulatory processes (phase two), research and experimentation (phase three), finalisation for product launch (phase four), and product launch and assessment (phase five). Conclusions: By following our five-phase guide, innovators may better navigate the complexities of integrating transformative surgical technologies into Australian healthcare. Although there are limitations, this approach is based on the validated Medtech Innovation Guide and may help both experienced and inexperienced practitioners better implement innovative technology; however, real-world validation is required. Full article

The dynamic response of pump valve motion directly influences the volumetric efficiency of drilling pumps and serves as a critical factor in performance enhancement. This study presents a coupled fluid–structure interaction (FSI) analysis of a novel secondary cushioned pump valve for drilling systems. A validated 3D transient numerical model, integrating piston–valve kinematic coupling and clearance threshold modeling, was developed to resolve the dynamic interactions between reciprocating mechanisms and turbulent flow fields. The methodology addresses critical limitations in conventional valve closure simulations by incorporating a geometrically adaptive mesh refinement strategy while maintaining computational stability. Transient velocity profiles confirm complete sealing integrity with near-zero leakage (<0.01 m/s), while a 39.3 MPa inter-pipeline pressure differential induces 16% higher jet velocities in suction valves compared to discharge counterparts. The secondary cushioned valve design reduces closure hysteresis by 22%, enhancing volumetric efficiency under rated conditions. Parametric studies reveal structural dominance, with increases in cylindrical spring stiffness lowering discharge valve lift by 7.2% and velocity amplitude by 2.74%, while wave spring optimization (24% stiffness enhancement) eliminates pressure decay and reduces perturbations by 90%. Operational sensitivity analysis demonstrates stroke frequency as a critical failure determinant: elevating speed from 90 to 120 rpm amplifies suction valve peak velocity by 59.87% and initial closing shock by 129.07%. Transient flow simulations validate configuration-dependent performance, showing 6.3 ± 0.1% flow rate deviations from theoretical predictions (Q_{t_max} = 40.0316 kg/s) due to kinematic hysteresis. This study establishes spring parameter modulation as a key strategy for balancing flow stability and mitigating cushioning-induced oscillations. These findings provide actionable insights for optimizing high-pressure pump systems through hysteresis control and parametric adaptation. Full article

Airports are complex environments where efficient localization and intelligent traffic management are essential for ensuring smooth navigation and operational efficiency for both pedestrians and Autonomous Guided Vehicles (AGVs). This study presents an Artificial Intelligence (AI)-driven airport traffic management system that integrates Visible Light Communication (VLC), rerouting techniques, and adaptive reward mechanisms to optimize traffic flow, reduce congestion, and enhance safety. VLC-enabled luminaires serve as transmission points for location-specific guidance, forming a hybrid mesh network based on tetrachromatic LEDs with On-Off Keying (OOK) modulation and SiC optical receivers. AI agents, driven by Deep Reinforcement Learning (DRL), continuously analyze traffic conditions, apply adaptive rewards to improve decision-making, and dynamically reroute agents to balance traffic loads and avoid bottlenecks. Traffic states are encoded and processed through Q-learning algorithms, enabling intelligent phase activation and responsive control strategies. Simulation results confirm that the proposed system enables more balanced green time allocation, with reductions of up to 43% in vehicle-prioritized phases (e.g., Phase 1 at C1) to accommodate pedestrian flows. These adjustments lead to improved route planning, reduced halting times, and enhanced coordination between AGVs and pedestrian traffic across multiple intersections. Additionally, traffic flow responsiveness is preserved, with critical clearance phases maintaining stability or showing slight increases despite pedestrian prioritization. Simulation results confirm improved route planning, reduced halting times, and enhanced coordination between AGVs and pedestrian flows. The system also enables accurate indoor localization without relying on a Global Positioning System (GPS), supporting seamless movement and operational optimization. By combining VLC, adaptive AI models, and rerouting strategies, the proposed approach contributes to safer, more efficient, and human-centered airport mobility. Full article

Time-varying mesh stiffness (TVMS) of the internal mesh transmission is a significant source of excitation that causes vibration and noise in planetary gear systems, and is also an important parameter in dynamics analysis. Currently, the calculation of mesh stiffness for internal gear pairs primarily relies on finite element simulation, and there still lacks a mesh stiffness analytical model that accounts for tooth surface nonlinear contact. Therefore, this paper proposes an analytical model for nonlinear contact mesh stiffness that comprehensively accounts for tooth surface modification and the flexibility of the ring gear. Firstly, a mesh stiffness calculation model for a sliced tooth pair was established using the potential energy method, which accounted for the influence of gear ring flexibility. Secondly, the tooth deviation ease-off diagram was derived from the modified tooth surface equations, which provided data support for the nonlinear contact analysis. On this basis, slicing element pairs that met the contact conditions were identified by combining elastic deformation with mesh clearance. The comprehensive mesh stiffness in nonlinear contact was calculated by integrating the deformation coordination equation with the principle of minimum potential energy. Finally, using a group of internal helical gear pairs as an example, the validity of the proposed method was verified through finite element simulation. The effects of load, modification amount, and face width on the TVMS and load transmission error (LTE) of an internal helical gear pair were investigated by the analytical model. The results show that the analytical model can provide a reference for the optimal design of internal gear transmission. Full article

Turbines are rotating machines that generate power by the expansion of a fluid; due to their characteristics, these turbomachines are widely applied in aerospace propulsion systems. Due to the clearance between the rotor blade tip and casing, there is a leakage flow from the blade pressure to the suction sides, which generates energy loss. There are different strategies that can be applied to avoid part of this loss; one of them is the application of so-called desensitization techniques. The application of these techniques on gas turbines has been widely evaluated; however, there is a lack of analyses of hydraulic turbines. This study is a continuation of earlier analyses conducted during the first stage of the hydraulic axial turbine used in the low-pressure oxidizer turbopump (LPOTP) of the space shuttle main engine (SSME). The previous work analyzed the application of squealer geometries at the rotor tip. In the present paper, winglet geometry techniques are investigated based on three-dimensional flowfield calculations. The commercial CFX v.19.2 and ICEM v.19.2 software were used, respectively, on the numerical simulations and computational mesh generation. Experimental results published by the National Aeronautics and Space Administration (NASA) and data from previous works were used on the computational model validation. The parametric analysis was conducted by varying the thickness and width of the winglet. The results obtained show that by increasing the winglet thickness, the stage efficiency is also increased. However, the geometric dimension of its width has minimal impact on this result. An average efficiency increase of 2.0% was observed across the entire turbine operational range. In the case of the squealer, for the design point, the maximum efficiency improvement was 1.62%, compared to the current improvement of 2.23% using the winglet desensitization technique. It was found that the proposed geometries application also changes the cavitation occurrence along the stage, which is a relevant result, since it can impact the turbine life cycle. Full article

The nonlinear contact force between gears and bearings exhibits intricate dynamics. This paper focuses on the coupling relationship between the time-varying meshing parameters of the gears, dynamic backlash, and dynamic bearing clearance in gear-bearing transmission systems. A dynamic model of a gear-bearing transmission system considering dynamic meshing parameters is established. The coupling mechanism between meshing stiffness, gear backlash, bearing clearance, and gear vibration response in gear transmission systems is analyzed. The results demonstrate a negative correlation between the gears’ geometric center distance and meshing stiffness amplitude. Gear vibration can affect the relative position of the gears. Changes in the relative position of the gears lead to an increase in the number of frequency components in the frequency domain of gear meshing stiffness. During gear rotation, the meshing parameters of the gears and tooth side clearance fluctuate with gear vibration. With increasing speed, the model’s dynamic meshing parameters also increase accordingly. The model achieves a feedback calculation of the system parameters and vibration responses in gear-bearing system dynamics. Full article

Mining dump trucks play an important role in engineering construction and resource extraction. Current research mainly focuses on the dynamic modeling and reliability analysis of the vehicle frame, suspension and overall model. However, with the development of electric drive, the wheel hub system has become an important component in mining truck equipment. This paper investigates the multi-body modeling of a mining truck’s hub drive reduction system in order to analyze its output characteristics including the stability of the angular velocity of its planetary carriers and the fluctuations in its meshing forces. A bench experiment was also conducted to verify the accuracy and stability of the proposed modeling. And the simulation results revealed that the fluctuations in the angular velocity of the planetary carriers were primarily influenced by the excitation from the hub motor’s input and the meshing forces between the gears of the reducers, which were mainly determined by the contact stiffness, damping, and clearance value during gear contact. Full article

Gear skiving is a highly productive method for manufacturing gears, especially internal gears. Circular arc internal gears are important parts of Rotary Vector (RV) reducers and harmonic reducers. This study presents the implementation of the gear skiving technique using a cylindrical tool to enhance the precision and efficiency of machining circular arc internal gears. By establishing the mathematical model for skiving a circular arc internal gear based on the conjugation theory of two surfaces, the barrel-shaped conjugate surface was solved by deducing gear meshing equations. A design method is proposed for a cylindrical skiving tool by utilizing the barrel-shaped conjugate surface with an off-center tool position along the axis. The cutting edge of the tool rake face was then obtained through cubic spline interpolation from the conjugate surface. The influence of the tool rake face offsets on the cutting rake angle and clearance angle is also discussed by defining the normal cutting plane of the tool. The correctness of the proposed cylindrical skiving tool was validated through simulation and actual skiving experiments. The experimental results demonstrated that the tooth profile error of the gear fell within ±0.004 mm, thereby satisfying the accuracy requirement for pin wheel housing gears. These research findings can contribute to advancements in novel cylindrical skiving tools. Full article