Search Results (212)

Overall sitting comfort is related to both static pressure distribution and dynamic human–seat interaction during vibration. This study proposes a simplified finite-element model of the seated human body that could potentially be used to assess overall sitting comfort. The static pressures of the seated human body measured on a rigid seat with different footrest layouts, together with the overall and localised apparent masses of the human body measured in a previous study, were used for model validation. The proposed model contained homogeneous soft tissues of the buttocks and thighs and rigid bodies connected to represent the torso. The tissue geometry was adjusted to match the measured anthropometry. Viscoelastic material was assigned to the tissues, and the properties were identified by fitting the modelled pressures and apparent masses to the measurement results. The proposed model was capable of reproducing static pressures and dynamic forces over the seat for the three sitting postures. Full article

Background: This study investigated sex differences in foot arch structure and function, and their impact on postural control and energy flow during dynamic tasks. Findings aim to inform sex-specific training, movement assessment, and injury prevention strategies. Methods: A total of 108 participants (53 males and 55 females) underwent foot arch morphological assessments and performed a sit-to-stand (STS). Motion data were collected using an infrared motion capture system, three-dimensional force plates, and wireless surface electromyography. A rigid body model was constructed in Visual3D, and joint forces, segmental angular and linear velocities, center of pressure (COP), and center of mass (COM) were calculated using MATLAB. Segmental net energy was integrated to determine energy flow across different phases of the STS. Results: Arch stiffness was significantly higher in males. In terms of postural control, males exhibited significantly lower mediolateral COP frequency and anteroposterior COM peak velocity during the pre-seat-off phase, and lower COM displacement, peak velocity, and sample entropy during the post-seat-off phase compared to females. Conversely, males showed higher anteroposterior COM velocity before seat-off, and greater anteroposterior and vertical momentum after seat-off (p < 0.05). Regarding energy flow, males exhibited higher thigh muscle power, segmental net power during both phases, and greater shank joint power before seat-off. In contrast, females showed higher thigh joint power before seat-off and greater shank joint power after seat-off (p < 0.05). Conclusions: Significant sex differences in foot arch function influence postural control and energy transfer during STS. Compared to males, females rely on more frequent postural adjustments to compensate for lower arch stiffness, which may increase mechanical loading on the knee and ankle and elevate injury risk. Full article

The Jiapigou mining district, a world-famous gold-producing district with a capacity that greatly exceeds 180 t Au, has a mining history longer than 200 years. The large amount of Jurassic Au mineralization in this district significantly differs from that in other districts of the North China Craton (130–115 Ma). However, the deep-seated dynamic processes and mechanisms that triggered the unique Jurassic mineralization in the Jiapigou district are poorly understood. Here, we present new data on the geology, petrography, and zircon U–Pb and Lu–Hf isotopes of the typical Huangnihe pluton in the Jiapigou district to address the above issues. The results revealed the following: (1) The Huangnihe pluton comprises mainly fine-grained granite and porphyritic granite, which were emplaced at 187 ± 2 Ma (n = 13) and 166 ± 2 Ma (n = 15), respectively. (2) The Hf isotope data indicate that the two episodes of granites exhibit distinct origins: the former (εHf(t) = −1.4 to +5.3; T_DM2 = 1784–1181 Ma) originated from juvenile lower crust, whereas the latter (εHf(t) = −14.9 to −9.7; T_DM2 = 2987–2518 Ma) was derived from Archean crust. (3) On the basis of published geochemical data, the estimated crustal thicknesses of the Jiapigou district ca. 187 Ma, ca. 175 Ma, and ca. 166 Ma ranged from 45 to 52 km, 43 km, and 58 to 63 km, respectively. Combined with regional observations, the results of this study further reveal the following: (1) The Jurassic magmatism in the Jiapigou district can be subdivided into three episodes: 187–186 Ma, ca. 175 Ma, and 166–165 Ma. (2) The crust in the Jiapigou district gradually thickened during the Jurassic and underwent partial melting during multiple episodes of Paleo-Pacific Plate subduction, thereby generating arc-like calc-alkaline (ca. 187 Ma), adakite-like (ca. 175 Ma), and adakite magmas (ca. 166 Ma) that were emplaced to form corresponding granitoids. Moreover, syn-ore magma mixing between the ca. 175 Ma adakite-like felsic magma and mantle-derived mafic magmas was considered a crucial process in magma evolution. This process in turn promoted the enrichment of ore-forming elements within the magma system, which significantly contributed to the formation of the large Au mineralization in the Jiapigou district. Full article

Active Speaker Localization (ASL) involves identifying both who is speaking and where they are speaking from within audiovisual content. This capability is crucial in constrained and acoustically challenging environments, such as aircraft cabins during in-flight medical emergencies. In this paper, we propose a novel end-to-end Cross-Modal Audio–Visual Fusion Network (CMAVFN) designed specifically for ASL under real-world aviation conditions, which are characterized by engine noise, dynamic lighting, occlusions from seats or oxygen masks, and frequent speaker turnover. Our model directly processes raw video frames and multi-channel ambient audio, eliminating the need for intermediate face detection pipelines. It anchors spatially resolved visual features with directional audio cues using a cross-modal attention mechanism. To enhance spatiotemporal reasoning, we introduce a dual-branch localization decoder and a cross-modal auxiliary supervision loss. Extensive experiments on public datasets (AVA-ActiveSpeaker, EasyCom) and our domain-specific AirCabin-ASL benchmark demonstrate that CMAVFN achieves robust speaker localization in noisy, occluded, and multi-speaker aviation scenarios. This framework offers a practical foundation for speech-driven interaction systems in aircraft cabins, enabling applications such as real-time crew assistance, voice-based medical documentation, and intelligent in-flight health monitoring. Full article

Conventional throttling valves have non-linear flow characteristics. However, in precise processes of flow control requiring them, appropriate flow modulations are necessary to enable a linear flow response even under partial valve actuations. This paper formulates a hydraulic conical valve configuration that exhibits linear flow. Flow studies were conducted on a 24 mm orifice-sized Conventional Conical Valve (CCV) using Computational Fluid Dynamics (CFD) analysis with commercial code ANSYS Fluent 2022 R1 and through experiments. The mass flow curve for the CCV had a convex upward shape, implying that at all valve openings, its discharges lay above the linear discharge line. To create greater resistance to flow, a venturi was incorporated into the valve casing close to the downstream side of the valve seat, leading to a Venturi Conical Valve (VCV). CFD analysis revealed that the addition of the venturi added more flow resistance, while the identified optimal VCV was still unable to make the flow linear. Subsequently, labyrinth cavities were machined on the conical valve body of the VCV, changing it into a Labyrinth Venturi Conical Valve (LVCV). Experiments revealed that the discharge curve for the identified LVCV was nearly linear. The maximum linearity deviation of 45.76% found in the CCV decreased to 9.95% in the LVCV. The reduction in linearity deviation indicates an improved closeness of the valve discharge to the linear conditions. Full article

Gravity anomalies caused by tectonics are commonly assumed to be static, based on the argument that the motions are slow enough for the induced mass changes over time to be negligible. We exploit this concept in the context of rifting and subduction by showing that the horizontal motions of density contrasts occurring at active and passive margins are responsible for sizable amounts of gravity rate of change. These findings are obtained via 2D finite element modeling of the two tectonic mechanisms in a vertical cross-section perpendicular to the ocean–continent transition as well as through evaluating the time-dependent gravity disturbance at a reference height caused by mass readjustment underneath. This disturbance originates from deep-seated changing density anomalies and dynamic topography with respect to a reference normal Earth. The gravity rate of change is proven to scale linearly with extensional and trench migration velocity; the peak-to-peak values between the largest maxima and minima are 0.08 μGal/yr and 0.21 μGal/yr, for a velocity of 1 cm/yr. For both tectonic mechanisms, the dominant positive rate of change is due to the horizontal motion of a density contrast of about 300–400 kg/m³. We also consider the role of dynamic topography in comparison to that of deep-seated changing density anomalies. Full article

Out-of-position (OOP) testing is increasingly important due to the development of autonomous vehicles, innovative car seat designs, and the need to verify safety in various seating configurations. This study analyzes the impact of seatback recline angle and crash pulse magnitude on head injury risk during rear-end impacts, focusing on the Head Injury Criterion (HIC). Using a sled system and a Hybrid III 50th-percentile dummy, 12 crash scenarios were examined with crash pulses of 10 g, 15 g, and 20 g and seatback recline angles of 21°, 25°, 38°, and 55°. The results showed that increasing the seatback recline angle reduces peak head accelerations but extends their duration, which, based on the Wayne State Tolerance Curve (WSTC), may increase injury risk. The HIC increased nonlinearly with higher crash pulses, especially in upright positions. The study proposes the Pelvis-to-Headrest Transmission Effect as a newly observed dynamic mechanism affecting head and neck injury risk. Findings suggest that a more reclined posture may enhance biomechanical safety in rear-end collisions, although the effect is complex and depends on multiple factors. Video analysis and Z-axis acceleration data confirmed that certain reclined configurations can increase compressive forces on the cervical spine, highlighting the need for comprehensive safety assessment. Full article

This paper innovatively constructs a comprehensive material cycle network framework for the circular economy system of the coal industry and evaluates the circular economy efficiency of China’s provincial coal industry from 2011 to 2021 using a comprehensive evaluation model that integrates emergy analysis and dynamic network data envelopment analysis (DEA). The research delves into the evolutionary characteristics of the coal industry’s circular economy and identifies the underlying causes of inefficiency. The results reveal that the circular economy in China’s coal industry has gone through three stages: the transformation period, the reinforcement period, and the growth period, with the inefficiency of waste reutilization being the key factor restricting the overall improvement in efficiency. The circular economy model in the production phase is gradually shifting from an extensive linear model to a clean, closed-loop model, while a significant gap remains between the high-emission linear model and the low-pollution closed-loop model in the utilization phase. Furthermore, regional heterogeneity mainly arises from imbalances in the operational efficiency of the circular economy system. This study not only reveals the deep-seated reasons for the low efficiency of circular economy in China’s coal industry but also provides strategies and directions for achieving a more efficient circular economy and carbon mitigation goals. Full article

This study numerically investigated how varying pulse durations of water mist systems influence fire dynamics in long, narrow underground enclosures. A Fire Dynamics Simulator (FDS) model was built to represent a pulse-actuated, fine water mist test rig, and simulations of oil pan fires were performed to quantify the evolution of temperature and radiative heat flux. Results show that an 8 s spray followed by an 8 s pause yields the most effective suppression cycle. When spray and pause durations are equal, periodic momentum exchange resonates with the buoyant plume, intensifying the mixing of gas and enhancing cooling near the fire seat. Compared with continuous discharge, pulsed mist generates stronger buoyancy-driven disturbances and delivers superior performance in terms of local heat’s extraction and extinguishment. This study has, for the first time, determined the optimal pulse cycle (8 s spray/8 s stop) for oil pool fires in narrow and long underground spaces through FDS simulation, and revealed the enhancement effect of the gas disturbance resonance mechanism on fire suppression efficiency. Full article

The phenomenon of global population aging poses considerable mobility challenges for older adults, particularly in cold climate regions, where the accessibility and configuration of street elements exert a significant impact on social participation and safety during severe winter conditions. Employing a combination of non-participatory observation, behavior mapping, and spatial analysis across different winter periods, this study investigates three residential streets in Harbin, China. The research systematically documents the types, frequencies, and spatial distributions of both social activities and street infrastructure utilized by the elderly. Subsequently, kernel density overlays of elderly social activity and street element distributions enable a nuanced analysis of the influence of environmental features on older adults’ social engagement throughout the three delineated winter phases. The findings reveal the following: (1) There is persistent demand for outdoor social interaction among the elderly, with participation rates inversely proportional to the severity of winter, peaking in early winter and declining through late and harsh winter stages; (2) Variations in activity types and durations are closely associated with spatial configurations: dynamic activities are predominantly observed along linear street segments, whereas passive behaviors cluster at intersections and broader street expanses; (3) There are several key aspects of street design and street furniture provision that help to support the use of streets in winter by the elderly. However, the influence of seating and fitness elements on mobile activities is limited. This study contributes to promoting inclusive urban design for older people in cold climates. Full article

This study presents an advanced simulation-based methodology for evaluating the dynamic vibrational behavior of the operator–vehicle assembly in autonomous electric agricultural tractors. Using the TE-0 electric tractor as the experimental platform, the research is structured into three integrated stages. In the first stage, a seated anthropometric virtual model of the human operator is developed based on experimental data and biomechanical validation. The second stage involves a detailed modal analysis of the TE-0 electric tractor using Altair Sim Solid, with the objective of determining the natural frequencies and vibration modes in the [0–80] Hz range, in compliance with ISO 2631-1. This analysis captures both the structural-induced frequencies—associated with the chassis, wheelbase, and metallic frame—and the operational-induced frequencies, influenced by the velocity and terrain profile. Subsequently, the modal analysis of the “Grammer Cabin Seat” is conducted to assess its dynamic response and identify critical vibration modes, highlighting how the seat behaves under vibrational stimuli from the tractor and terrain. The third stage extends the analysis to the virtual operator model seated on the tractor seat, investigating the biomechanical response of the human body and the operator–seat–vehicle interaction during simulated motion. Simulations were carried out using SolidWorks 2023 and Altair Sim Solid over a frequency range of [0–80] Hz, corresponding to operation on unprocessed soil covered with grass, at a constant forward speed of 7 km/h. The results reveal critical resonance modes and vibration transmission paths that may impact operator health, comfort, and system performance. The research contributes to the development of safer, more ergonomic, and sustainable autonomous agricultural transport systems. By simulating real-world operation scenarios and integrating a rigorously validated experimental protocol—including vibration data acquisition, biomechanical modeling, and multi-stage modal analysis—this study demonstrates the importance of advanced modeling in optimizing system-level performance, minimizing harmful vibrations, and supporting the transition toward resilient and eco-efficient electric tractor platforms in smart agricultural mobility. Full article

Human–wildlife conflict (HWC) is intensifying in Japan, driven by complex socio-ecological changes. While the Social–Ecological Systems (SES) framework offers a valuable analytical tool, standard applications often fail to capture the crucial cultural specificities, demographic pressures, and institutional dynamics that define the Japanese context. This paper addresses these limitations by conducting a scoping review of academic and policy literature in order to synthesize the evidence needed to develop a culturally and institutionally attuned adaptation of the SES framework. The review’s findings confirm that profound demographic change (kaso and kōreika), unique institutional arrangements (the Ryōyūkai crisis), deep-seated cultural values, and asymmetric power relations are core systemic drivers of HWC, not external factors. Building on this evidence, we propose a theoretically grounded adapted framework that internalizes these factors as endogenous variables. The resulting framework serves as a more robust diagnostic tool for understanding and navigating HWC in Japan. It facilitates the identification of context-specific leverage points and offers a transferable methodological model for adapting SES analysis to other culturally distinct and rapidly changing societies. Full article

This study proposes an improved formulation of the blade element momentum theory (BEMT) to enhance its robustness and versatility for urban/advanced air mobility (UAM/AAM) applications. A new velocity factor was introduced to eliminate numerical singularity issue under low inflow velocity conditions. The BEMT framework was further extended and modified to account for non-axial inflow and descent flight conditions. The proposed approach was validated for an isolated propeller case by comparing the results with wind tunnel test data and the computational fluid dynamics (CFD) based on both the overset mesh and sliding mesh methods. The improved BEMT provided reliable accuracy even in low inflow velocity conditions where basic BEMT fails to converge, and yielded reasonable performance predictions with respect to the sliding mesh results. The practicality of the method was confirmed through further application studies such as analyzing on the tilt propeller of single-seated UAM along its mission profile and constructing a propeller performance database for the lift and propulsion propellers of a lift and cruise type 5-seated UAM. The improved BEMT exhibited satisfactory engineering-level accuracy for various flight conditions, with prediction errors within 14% of the CFD results. The results and observations indicate that the proposed BEMT framework is suitable for use in the early design stages, performance analysis, and construction of a performance database, for distributed propulsion aircraft, such as eVTOL and UAM/AAM. Full article

This study proposes an equivalent furniture fire model based on standard combustible assembly and verifies its feasibility as a substitute for real furniture through full-scale experiments and numerical simulations. Experiments show that the peak heat release rate and total heat release of the standard combustible assembly are highly consistent with those of the single-seat sofa. The numerical model has been verified by experimental data. The dynamic characteristics of the heat release rate (HRR) curve are consistent with the temperature evolution process, confirming its reliability for the numerical model. The research on optimizing fire extinguishing parameters is carried out based on this numerical simulation. The results show that the response time of the horizontal sprinkler is 22 s shorter than that of the vertical sprinkler, and the fire extinguishing efficiency is improved. Reducing the sprinkler height to 3 m can accelerate activation and reduce CO₂ release. A flow rate of 91.4 L/min can effectively control the fire, but when it exceeds 150 L/min, the fire extinguishing efficiency is significantly reduced. The low response time index sprinkler starts up 88 s faster than the standard type, significantly enhancing the initial fire suppression capability. This scheme provides a safe, economical, and repeatable standardized combustible assembly for fire training and offers theoretical support for the parameter design of intelligent fire extinguishing systems. Full article

The saddle’s adaptability to the rider–horse pair’s biomechanics is essential for equestrian comfort and performance. However, approaches to dynamic evaluation of saddle fitting are still limited in equestrian conditions. The purpose of this study is to propose a method of quantifying saddle adaptation to the rider–horse pair in motion. Eight rider–horse pairs were tested using four similar saddles with small modifications (seat depth, flap width, and front panel thickness). Seven inertial sensors were attached to the riders and horses to measure the active range of motion of the horses’ forelimbs and hindlimbs, stride duration, active range of motion of the rider’s pelvis, and rider–horse interaction. The results reveal that even small saddle changes affect the pair’s biomechanics. Some saddle configurations limit the limbs’ active range of motion, lengthen strides, or modify the rider’s pelvic motion. The temporal offset between the movements of the horse and the rider changes depending on the saddle modifications. These findings support the effect of fine saddle changes on the locomotion and synchronization of the rider–horse pair. The use of inertial sensors can be a potential way for quantifying the influence of dynamic saddle fitting and optimizing saddle adaptability in stable conditions with saddle fitter constraints. Full article