Search Results (1,835)

The goaf backfilling with the coal gangue is an effective strategy for mitigating the mining-induced surface subsidence and reducing the solid waste accumulation. However, the conventional backfilling methods often suffer from limited transport efficiency, poor material distribution, and high operational cost. The present paper proposes a novel technique using an inclined spiral propeller to propel the gangue particles into the goaf, aiming to improve both the backfill rate and spatial uniformity. A three-dimensional parametric model of the inclined screw conveyor is developed, and the discrete element method (DEM) is employed to simulate the dynamic transport and placement of the gangue particles. An L9 ($3^3$) orthogonal experimental design is implemented to systematically evaluate the effects of the rotational speed (240, 300, 360 r/min), inclination angle ($30°$, $45°$, $60°$), and screw pitch (180, 240, 300 mm) on the two critical performance indicators, namely, filling mass and spreading coverage area. The range analysis and matrix analysis are performed to determine the primary influencing factors and to identify the optimal parameter combination for the multi-objective performance. The results show that the inclination angle is the dominant factor for the filling mass, with a $60°$ angle yielding the highest throughput (38.60 kg). In contrast, the rotational speed is the dominant factor for the spreading coverage area, where an increase from 240 to 360 r/min nearly triples the covered area. The optimal compromise for the comprehensive backfilling performance is the rotational speed 360 r/min, inclination angle $60°$, and screw pitch 300 mm, which simultaneously achieves the high transport capacity (36.65 kg) and the largest spreading area (2.87 ${\mathrm{m}}^2$). The present study provides a theoretical and methodological foundation for the engineering design of efficient, low-cost goaf backfilling systems. Full article

The article presents an original approach to automatic musical key detection, combining Constant-Q Transform (CQT) analysis with the Triple Composite Signature of Fifths (TCSF). The method’s novelty lies primarily in the construction of the Signature of Fifths (SF), which is grounded in fundamental principles of music theory and builds on earlier SF-based studies. The proposed approach aims to preserve the algorithmic simplicity typical of SF approaches while strengthening their key advantages. In addition, the method reflects the analytical approach of experienced musicians by assigning greater importance to the initial and final sections of a piece. The use of CQT enables efficient audio analysis and offers a practical compromise between frequency resolution and alignment with the pitch-class representation. Experiments conducted on Franz Schubert’s songs from the Winterreise song cycle and Frédéric Chopin’s Preludes, Op. 28, confirm the effectiveness of the proposed algorithm, achieving 87.5% and 79.2% key-detection accuracy, respectively. The obtained results demonstrate that the proposed method is competitive with tonal profile-based key-detection approaches. Full article

This study consists of two main components. The first part establishes a seakeeping assessment method, while the second part focuses on hull-form optimization with seakeeping performance as the objective. For the seakeeping analysis, the Lewis conformal mapping method is used to calculate the sectional hydrodynamic coefficients. Strip theory is then applied to obtain the global hydrodynamic coefficients of the hull. The coupled heave and pitch motion responses are calculated and compared with nonlinear time-domain simulation results and experimental data, showing good agreement. A multivariate linear regression model is established to approximate the relationship between the principal hull-form parameters and the heave and pitch RAOs. The comparison between the regression model and strip theory results shows that the prediction error remains within 5%, indicating that the regression model can provide an efficient surrogate objective function for hull-form optimization. The particle swarm optimization (PSO) algorithm is then employed to optimize the hull form, with the ship length, breadth, draft, and block coefficient considered as design variables. To further evaluate the optimized hull, additional calculations are conducted under different Froude numbers and encounter angles. Under head sea conditions with varying Froude numbers, the optimized hull reduces the peak heave RAO by 11.6–31.1% and the peak pitch RAO by 8.6–17.9%. Under different encounter angles at F_r = 0.3, the reductions in peak heave and pitch RAOs are 31.1–33.9% and 16.5–18.8%, respectively. These results demonstrate that the proposed regression assisted PSO optimization framework can effectively reduce the heave and pitch responses of the Wigley hull under the investigated regular wave conditions. Full article

The vertical landing of quadrotor unmanned aerial vehicles (UAVs) involves highly transient impact dynamics that generate significant vibrations on the UAV body, particularly under uncertain touchdown conditions such as uneven terrain, asymmetric ground contact, and high-impact landing. In this study, a robust semi-active vibration control framework is proposed for a quadrotor UAV equipped with a four-point soft landing gear system. The UAV is modeled as a three-degree-of-freedom rigid body including heave, pitch, and roll motions, while each landing gear leg is represented by an equivalent spring-damper mechanism with adaptively controllable damping characteristics. To evaluate the effectiveness of the proposed framework, PID (Proportional–Integral–Derivative), GA-PID (Genetic Algorithm-Based Proportional–Integral–Derivative), Fuzzy–PID (Fuzzy Logic-Based Proportional–Integral–Derivative), and ANFIS-PID (Adaptive Neuro-Fuzzy Inference System-Based Proportional–Integral–Derivative) controllers are comparatively investigated under five different landing scenarios. The nonlinear touchdown dynamics are implemented in the MATLAB/Simulink environment using a state-space-based simulation model. The results demonstrate that intelligent adaptive control methods significantly improve landing stability and vibration attenuation compared to the conventional PID controller. Among all methods, the ANFIS-PID controller achieved the best overall performance. Under the most severe landing condition, the peak vertical displacement was reduced from 0.114 m to 0.025 m, while the maximum pitch and roll angles decreased from approximately 11° to nearly 2°. Additionally, the settling time was reduced from nearly 10 s to below 3 s. Full article

Maintaining structural stability and reliable mooring performance remains a key challenge for offshore floating photovoltaic (FPV) systems. This study investigates the coupled hydrodynamic and mooring behavior of a novel large-scale hexagonal rigid FPV platform through 1:25-scale physical model tests. A near-zero-pre-tension slack mooring arrangement was adopted to isolate the effects of mooring type, including anchor chain (M1), steel cable (M2), and elastic cable (M3). The results show that the influence of mooring configuration is strongly degree-of-freedom dependent. Surge motion is highly sensitive to mooring type, whereas heave and pitch remain largely consistent among the three cases. In regular waves, the maximum surge-acceleration RAO of M2 is 1.82 and 2.27 times those of M1 and M3, respectively. Peak mooring tension shows a strong correlation with maximum surge acceleration in both regular and irregular waves, indicating that surge motion can serve as a useful indicator of extreme mooring loads under similar slack-mooring conditions. Among the three configurations, M1 exhibits the strongest short-term peak-load buffering. Under extreme irregular waves, its peak mooring tension is 82.4% and 24.7% lower than those of M2 and M3, respectively. These results provide experimental guidance for the mooring design of large-scale rigid FPV systems. Full article

Because large language models operate through language, they rely on self-reports to access the feeling of understanding, limiting their ability to support students’ learning. A previous study explored whether facial expressions could provide an alternative way of measuring this feeling across phases of understanding in an academic context, but it had limited success. To examine how effective other physiological channels may be in measuring the feeling of understanding, this study investigated whether acoustic feature patterns are associated with nascent understanding, misunderstanding, confusion, emergent understanding, deep understanding, and underconfidence as 198 participants completed a literary analysis task while their speech was recorded over Zoom. CatBoost and logistic regression models showed modest performance, indicating that phases of understanding were not reliably distinguishable at the population level. In contrast, within-person analyses revealed consistent differences between nascent and emergent understanding across several acoustic features, including pitch, jitter, shimmer, and spectral flux. The findings show that acoustic features of speech do not reliably distinguish phases of understanding at the population level in naturalistic academic contexts but do reflect consistent within-person differences between nascent and emergent understanding, highlighting both the potential and the limits of using speech as a physiological measure of the feeling of understanding and pointing to the need for alternative ways to operationalize this feeling as it unfolds across phases. Full article

Gas Electron Multiplier (GEM) detectors have become an indispensable component of modern tracking systems. The heart of a GEM detector is a thin polyimide foil (∼50 µm) clad with copper (∼5 µm) on both sides and containing an array of regularly spaced holes (typically diameter of ∼70 µm and pitch of ∼140 µm) fabricated using photolithographic techniques. The presence of the dielectric substrate (polyimide) within the amplification region introduces a time dependent response when the detector is exposed to external irradiation, a phenomenon commonly referred to as the charging-up effect. This effect arises from the accumulation of charge on the insulating polyimide surfaces, leading to a gradual modification of the local electric field configuration inside the GEM holes and, consequently, a variation in the detector gain over time. The charging-up behaviour has been systematically investigated for triple GEM chamber prototypes using an Fe-55 radioactive source (5.9 keV X-rays) with an activity of ∼20 mCi. The characteristic charging-up time constant has been extracted, and its dependence on detector gain and irradiation rate has been examined. In addition, the uniformity of detector performance in terms of count rate, gain, and energy resolution has been studied both before and after the charging-up process. In this review article, the experimental setup, data acquisition methodology, and analysis procedures developed and carried out by our group are summarised. The key findings reported by other groups, relevant Monte Carlo simulation efforts, and future outlook for the charging-up investigation on GEM based detectors are also discussed in this article. The investigations and their outcomes reviewed here provide valuable insight into the charging-up dynamics of GEM detectors and their dependence on operational parameters. Full article

In order to optimize the sealing structure of the electrolytic cell for hydrogen production by electrolysis of water and enhance its sealing performance, a finite element model of the electrolytic cell sealing was established using software. The influence of different parameters of the sealing rib structure on the sealing performance was studied, and the variation law of gasket compressive stress under different sealing rib slot widths, angles, and spacings was explored. The results show that under the material constants of C10 = 7.0 × 10⁻³ and C01 = 6.05 in the Mooney–Rivlin constitutive model of the gasket, the gasket will deform and embed into the sealing rib groove after compression. At the same time, two parts of stress concentration will occur at the contact area between the gasket and the sealing rib groove, namely tensile stress concentration and compressive stress concentration. This stress concentration is the main source of sealing effect in practical work. After adding the sealing rib groove, the contact area between the sealing rib area and the gasket increases. When maximizing the peak sealing compressive stress serves as the optimization criterion, the optimal pitch settles at 0.4 mm; if the optimization objective shifts to attaining the utmost contact area, the preferable spacing amounts to 1 mm, accompanied by a maximum contact area increment of 34.31 percent. After comprehensive deliberation over sealing stress magnitude, functional sealing area, gas tightness efficiency as well as practical engineering applicability, 0.8 mm is pinpointed in this dissertation as the globally optimal spacing dimension. With a sealing rib pitch of 0.8 mm, a breadth of 1 mm, and an inclined angle of 20 degrees, the gasket yields substantial sealing stress alongside optimized post-assembly sealing contact area, wherein 26.44 percent of the overall gasket area contributes to effective sealing performance. Full article

Continuous population growth will lead to further expansion and densification of urban environments. In this context, Urban Air Mobility (UAM) has emerged as a new transportation solution through the use of Vertical Take-Off and Landing (VTOL) aircraft, more precisely, configurations such as lift-plus-cruise tilt-rotors. During the conceptual design phase, propeller design methodologies commonly reported in the literature rely on vortex-based approaches or actuator disk theory. However, the accuracy of these methods strongly depends on the inflow angle and operating conditions. This paper introduces an analytical model to predict propeller thrust at a 90° inflow angle (edgewise flight), based on a correction of the thrust under axial flight conditions and the propeller geometry evaluated at 75% span. The approach relies on local velocity and angle of attack estimations derived from classical Blade Element Momentum Theory (BEMT) with an additional correction to account for stall effects at high angles of attack. This capability is particularly relevant for modeling lift-plus-cruise tilt-rotor configurations cruise phase during early design stages while maintaining minimal computational cost. The proposed model is validated against wind tunnel measurements for several propellers tested at different global pitch angles, varying from 0 m/s to 9.1 m/s of windspeed and 1300 to 6200 rpms, demonstrating the applicability of the developed formulation for blades with twist angles up to 16°. Full article

A computational fluid dynamics (CFD) analysis is conducted to systematically investigate heat transfer enhancement in tubes fitted with grooved twisted tapes and to identify the groove geometry that provides the best thermo-hydraulic performance. Three grooved twisted tape configurations—circular-grooved twisted tapes (CGTT), rectangular-grooved twisted tapes (RGTT), and triangular-grooved twisted tapes (TGTT)—are evaluated and compared with a smooth tube and a conventional twisted tape over a Reynolds number range of 5000–20,000 under isothermal wall conditions. The grooved twisted tapes enhance heat transfer through the combined effects of swirl-induced secondary flows and groove-generated flow disturbances, which intensify turbulent mixing and reduce the thickness of the thermal boundary layer. Compared with the plain tube, the grooved configurations increase the Nusselt number by 1.472–1.98 times while increasing the friction factor by 3.21–3.58 times. Relative to the conventional twisted tape, the grooved designs provide an additional 8.0–12.1% enhancement in heat transfer with only a marginal increase of 0.2–1.5% in friction factor. The thermodynamic analysis indicates that the CGTT configuration exhibits the lowest entropy generation rate and exergy loss throughout the investigated Reynolds number range. In particular, the CGTT achieves a Bejan number of 0.999841 at Re = 5000, demonstrating an excellent balance between heat transfer enhancement and frictional losses. Furthermore, the CGTT attains the highest thermal performance factor (TPF) of 1.294 at Re = 5000 and maintains TPF > 1.0 over the entire Reynolds number range. The overall performance ranking is consistently established as CGTT > TGTT > RGTT based on comprehensive analyses of velocity fields, streamline patterns, turbulent kinetic energy distributions, temperature contours, and thermodynamic characteristics. Although the present study identifies the circular-groove configuration as the optimal design for a twist ratio (y/W) of 3.0, further parametric investigations involving variations in twist ratio, groove dimensions, and groove pitch are required to develop generalized design guidelines. Full article

The integration density of photonic integrated circuits is fundamentally limited by evanescent field overlap and subsequent inter-channel crosstalk. Layered transition metal dichalcogenides (TMDCs) bypass these confinement constraints through intrinsic optical birefringence and high refractive indices. Here, we report the near-infrared optical constants and waveguide dispersion of molybdenum diselenide (MoSe₂). Ellipsometry performed on centimeter-scale crystals yields an in-plane refractive index of 4.1–4.7 over 1000–2000 nm, with an extinction coefficient close to the sensitivity limit of the fit away from strong excitonic resonances. To validate the anisotropic dielectric tensor at the device scale, scattering-type scanning near-field optical microscopy (s-SNOM) was utilized to map the propagation of transverse-magnetic modes in 235 nm thick exfoliated flakes. Spatial Fourier analysis of the edge-scattered near-field interference yields effective mode indices that precisely match the modeled dispersion. Using the verified dielectric tensor, finite-element simulations demonstrate that single-mode MoSe₂ waveguides optically outperform equivalent tungsten disulfide (WS₂) benchmarks. The enhanced evanescent field suppression in the claddings of MoSe₂ waveguide increases the coupling length by a factor of 3.5, reducing the required routing pitch and enabling a 12.5% direct increase in on-chip integration density. The results identify MoSe₂ as a high-index anisotropic platform for compact waveguiding in the near-infrared. Full article

To address the limited understanding of the aerodynamic characteristics of bird-inspired flapping-wing aircraft across different flight phases and the unclear flow field interaction mechanisms between the wings and tail, this study performs three-dimensional numerical simulations based on a self-developed prototype using ANSYS Fluent and the overset mesh method. The aerodynamic effects of key tail parameters under different flight conditions are quantitatively evaluated, and the mechanisms of bidirectional wing–tail aerodynamic coupling are investigated. The results show that tail twist has a negligible influence on instantaneous lift and thrust during level flight, with a maximum variation of only 0.2 N, but significantly affects the overall aerodynamic moments of the aircraft. When the tail twist angle increases from 15° to 20°, the pitching moment increases by 6%. In contrast, during climbing flight, the tail pitch angle has a pronounced effect on lift and thrust, and its aerodynamic influence depends strongly on the aircraft angle of attack. At an aircraft angle of attack of 15°, the difference between the maximum and minimum cycle-averaged pitching moments reaches 0.2 N·m. Further analysis of vorticity fields and pressure distributions confirms the existence of distinct wing–tail aerodynamic coupling. The tail not only directly modifies the aerodynamic forces and moments acting on the aircraft but also alters the wing-generated flow structures, while the wing wake simultaneously influences the aerodynamic effectiveness of the tail. This bidirectional wing–tail aerodynamic coupling plays a critical role in shaping the aerodynamic response of the aircraft under different flight conditions. These findings clarify the aerodynamic roles of key tail parameters and reveal the underlying flow field interaction mechanisms across different flight phases, providing a theoretical basis for motion-parameter optimization and precise attitude control of bird-inspired flapping-wing aircraft. Full article

To improve the path-following performance of an underactuated autonomous underwater vehicle (AUV) under varying path geometries and desired velocities, this study proposes a direct X-rudder control method based on Task-Informed Inductive-Bias Conservative Soft Actor–Critic (TIB-CSAC). The proposed method directly learns the X-rudder control policy from the path-following information of the current and subsequent path segments in a data-driven way, thereby avoiding the complex design and manual tuning of guidance laws and attitude controllers for rudder command generation. To support such two-segment policy learning, a task-informed inductive-bias encoder is proposed to construct structured and conditioned state representations, thereby improving sample efficiency and overall training quality. In addition, given the long-tail characteristics of task difficulty in agent training, a multi-head conservative value evaluation mechanism is incorporated to mitigate return drawdowns induced by challenging tasks in the tail stage of training and to enhance tail-stage convergence stability. The path-following performance is validated in three representative scenarios with different path pitch, path heading variations, and desired surge velocity conditions. The results show that, compared with the baseline soft actor–critic (SAC) method, TIB-CSAC improves multiple vertical and horizontal error metrics, including maximum absolute error, mean absolute error, tail error, and error threshold exceedance ratio. These results indicate that TIB-CSAC not only improves overall adherence to the reference path, but also more effectively suppresses extreme errors and tail errors, thereby demonstrating stronger path-following robustness and reliability. Full article

The accurate prediction of resistance and running attitudes of high-speed planing crafts is of great significance for the improvement of ship hydrodynamics. In this study, the lab model tests and computational fluid dynamics (CFD) methods are employed to investigate the effects of volumetric Froude number and longitudinal center of gravity (LCG) position on the resistance performance, motion characteristics, and free-surface wave patterns for a planing craft. The capability of the CFD model was validated through towing tank resistance tests conducted under various LCG conditions. A systematic analysis of the influence mechanism of LCG variation on the hydrodynamic performance of the craft was conducted. The results indicate that an aftward LCG position can improve the resistance performance; however, it also leads to an increase in the pitch angle. These findings can provide a foundation for the optimization design of high-speed planing craft. Full article

This study examines how auditory contexts, or soundscapes, shape chocolate taste perception, affective response, hedonic liking, and the extent to which emotion mediates these effects. Using a within-subjects design with 120 participants aged 18–25 years, four auditory conditions were compared: silence, natural soundscape, relatively low-pitched soundscape, and relatively high-pitched soundscape. Participants evaluated perceived bitterness, sweetness, acidity, emotional valence, arousal, and overall liking after tasting the same 65% dark chocolate under each auditory condition. The results showed that auditory context significantly modulated taste perception, affective response, and liking. The natural soundscape produced the most favorable profile, increasing liking and emotional valence while reducing arousal. In contrast, the relatively high-pitched condition increased arousal and enhanced perceived acidity (Δ ≈ 6.77 VAS points). Effect sizes indicated stronger effects on arousal (partial η² ≈ 0.46), liking (partial η² ≈ 0.29), acidity (partial η² ≈ 0.28), and valence (partial η² ≈ 0.26) than on sweetness perception (partial η² ≈ 0.05). Mediation analysis showed that emotional valence partially explained the relationship between the natural soundscape and liking, whereas arousal did not play a significant mediating role. These findings suggest that auditory environments influence chocolate evaluation through both affective and crossmodal pathways. Overall, the study provides controlled evidence that sound can function as a relevant contextual variable in multisensory chocolate-tasting experiences, with implications for sensory evaluation, gastronomy, and experience design. Full article