Search Results (313)

In order to solve the problems of stratification, segregation, and insufficient mixing uniformity of glass fiber raw materials in the process of pneumatic mixing, the binary particles of pyrophyllite and limestone, the core raw materials of E-glass fiber, were taken as the research object, and the influence of nozzle inclination angles (0°, 45°, 60°, 75°) on the gas–solid flow, particle motion and mixing performance in the pneumatic mixing tank was systematically investigated by using the CFD-DEM coupling method. The flow field evolution and mixing mechanism at different inclination angles were compared and analyzed by visualization of particle motion, gas flow streamlines, turbulent kinetic energy distribution, and quantitative characterization of Lacey mixing index (LMI) and particle axial concentration distribution. The results show that the nozzle inclination angle significantly regulates the flow field structure in the tank, the 0° vertical nozzle forms a single axial jet, with a low-speed dead zone at the top and particle accumulation, and the mixing index stabilizes only at 0.92. The 45°~75° inclined nozzle can induce the formation of a stable and symmetrical double-vortex circulation flow field, which strengthens the radial mixing of particles and the turbulent disturbance in the whole region. The LMI is stable above 0.97, and the mixing uniformity and stability are significantly improved. In particular, under the 45° inclination angle, the volume-averaged turbulent kinetic energy shows a counter-trend increase, with a relatively low flow dead zone and a uniform axial concentration distribution. The advantages of the oblique jet in reducing segregation, optimizing flow field, and improving mixing efficiency are clarified. It can provide a theoretical basis and numerical reference for the pneumatic mixing of glass fiber raw materials and the improvement of relevant equipment structure and process optimization. Full article

Facial expression recognition in the wild is challenged by both noisy supervision and degraded visual evidence: subtle expression cues must be interpreted under blur, contrast changes, image noise, and annotator disagreement. Existing noisy-label FER methods mainly regulate samples, labels, or attention, while frequency information is rarely used to adapt the semantic representation itself. We propose Frequency-Guided Expert Modulation (FARM-FER), which treats local and global frequency descriptors as a control signal rather than an additional classifier input. A joint Haar-DWT and radial-FFT context guides soft routing among nonlinear experts and channel-wise affine recalibration of the semantic feature, while a learned gate combines the two corrections before a lightweight classifier predicts the expression from the refined representation. Across RAF-DB, FER+, and AffectNet under symmetric label noise, with additional evaluations under class-dependent label noise on RAF-DB and native crowd-label ambiguity on FER+, FARM-FER consistently improves matched baselines. At 30% symmetric noise, FARM-FER reaches 89.18% accuracy on RAF-DB, with a 1.6% performance gain over the matched Swin-Tiny baseline; the gains also hold in a controlled ResNet18 reimplementation and in class-sensitive AffectNet evaluation. Measured cost analyses show only modest parameter and FLOP overhead, supporting a lightweight yet effective design in terms of model size and arithmetic cost for noisy-label FER. Full article

In this paper, we investigate densely defined Toeplitz composition operators $T_u{C}_{\phi }$ on the Fock space ${\mathcal{F}}^2$. We completely characterize the $J_{\lambda }$-complex symmetry of such operators and derive necessary and sufficient conditions for normality. We further establish full criteria for self-adjointness and construct an explicit example showing that an operator may be $J_{\lambda }$-complex symmetric without being normal. To extend the theory beyond fixed radial–trigonometric expansions, we combine the Gaussian-weighted Mellin transform with Adaptive Fourier Decomposition (AFD) and establish the unified AFD-Mellin Symmetry Criterion, which generalizes these symmetry characterizations to adaptive rational basis systems. Full article

The passage from generic (non-interacting) plasma to cold plasma with dust around a spherically symmetric black hole is newly analytically studied. The configurations are newly written, and the behaviours of the observer are this way spelt out. The conservation of mass flux and that of the energy flux are used. The velocities of the observer are newly classified in the case of (non-interacting) hot plasma with dust for the transition to a configuration of (non-interacting) cold plasma with dust. The suitable functional dependence of the radial component of the velocity of the observer is now expressed in order to select the configurations which allow for the transition. The passage to a configuration of (non-interacting) cold plasma with dust is proved to be defined after the suitable integration conditions of the mass flux and of the energy flux, plus the suitable functional dependence of the radial component of the velocity of the observer are found. The spherical accretion is newly written. The emissions of the new accretion mechanism are due to (1) the variation in the gravitational potential as from blue further studies of the Author; (2) the radiation due to the change in the gravitational potential as described in the Landau–Lifshitz–Pitaevskii equations; (3) the standard electrodynamics radiation; and (4) the radiation of the positron (quantum mechanism) from the electron–positron pair of the emitted photon (in the Landau–Lifshitz–Lindhard scheme). Full article

The thermal stability and devitrification pathway of melt-spun high-entropy Cr₁₆Mn₁₆Fe₁₆Co₁₆Ni₁₆P₂₀ metallic glass were investigated using transmission electron microscopy/selected-area electron diffraction (TEM/SAED), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and ⁵⁷Fe Mössbauer spectroscopy. TEM/SAED confirmed an amorphous ribbon structure, with diffuse rings and radial maxima at k₁ = 0.84799 nm⁻¹ and k₂ = 1.44459 nm⁻¹. Non-isothermal DSC revealed two exothermic events, Peak I at ~716–752 K and Peak II at ~881–930 K, both shifting to higher temperatures with increasing heating rate. Kissinger analysis yielded apparent activation energies of Ea₁ = 359.2 kJ/mol for Peak I and Ea₂ = 414.9 kJ/mol for Peak II. Specimens heated in the DSC under argon at 20 K/min to selected target temperatures were examined ex situ. The XRD patterns are consistent with the onset of crystallization during Peak I, with reflections tentatively attributed to an Fe₃P-type phase and an FCC solid solution. Peak II is associated with further phase evolution, including the development of reflections compatible with MnNi-type and Co₂P-type phases. Because of peak overlap in this multicomponent alloy, the proposed phase sequence should be regarded as a plausible interpretation based on combined DSC, XRD, and Mössbauer evidence rather than as a uniquely resolved quantitative phase analysis. Mössbauer spectra reveal three paramagnetic Fe environments. With increasing DSC target temperature, the high-QS Fe3 component, representing a highly distorted Fe environment, decreases systematically, whereas the low-QS Fe1 component, associated with a more symmetric, nearly cubic Fe environment, becomes dominant. The high apparent activation energies indicate a larger effective kinetic barrier than in many simpler transition-metal–phosphorus amorphous alloys. Full article

Circular tunnel linings are geometrically symmetric structures, whereas non-uniform external pressure and different steel–concrete layer arrangements may induce asymmetric stress redistribution. To distinguish the axisymmetric response from the asymmetric harmonic response, this study develops an analytical solution for a two-layer corrugated steel–concrete composite tunnel lining subjected to equivalent external pressure. The concrete layer is modeled as an isotropic elastic material, while the corrugated steel layer is represented as an equivalent cylindrically orthotropic material. The governing equations are formulated in polar coordinates under plane-strain conditions, and the solution is obtained by superposing the axisymmetric component and the harmonic component. Perfect bonding is assumed at the steel–concrete interface, where displacement, radial stress, and shear stress are continuous. The proposed analytical solution is verified using finite element models for three cases: a single-layer homogeneous lining under uniform pressure, a two-layer composite lining under uniform pressure, and a two-layer composite lining under non-uniform pressure. The analytical and finite element results show good agreement, confirming the mathematical consistency and implementation accuracy of the proposed formulation. Based on the verified solution, the effects of layer arrangement, corrugated steel stiffness ratio, and burial depth are investigated. The results show that the corrugated steel layer carries the dominant hoop stress in both layer arrangements. The inner corrugated steel arrangement may be more relevant to internal strengthening of existing tunnels, whereas the outer corrugated steel arrangement provides a useful reference for new composite linings dominated by external ground pressure. Increasing the stiffness ratio transfers more hoop stress to the steel layer and reduces the elastic stress and displacement responses of the concrete layer, although improvement becomes less significant at large stiffness ratios. Increasing burial depth mainly amplifies the response magnitude without changing the overall symmetry pattern. The proposed solution provides a closed-form benchmark for evaluating symmetry-related stress redistribution in corrugated steel–concrete composite tunnel linings within the linear-elastic range. Full article

Flexible manipulators have attracted increasing attention due to their lightweight structure, high flexibility, and energy efficiency, for which they are suitable for delicate and high-precision tasks. However, their control remains a problem because of strong nonlinearities and uncertainties in the system. Based on the trajectory tracking control problem of the single-link flexible manipulator (SLFM) system, this paper proposes a fractional order adaptive neural network control scheme for SLFM under symmetric time-varying full-state constraints. Firstly, a fractional-order dynamic model is established to better capture the inherent memory and nonlinear characteristics of the SLFM. Secondly, an adaptive radial basis function (RBF) neural network-based control scheme is developed within a backstepping framework, and a symmetric time-varying barrier Lyapunov function (BLF) is incorporated to guarantee that all system states remain within predefined bounds. In addition, command filters are introduced to avoid the “explosion of complexity” caused by backstepping. Next, theoretical analysis based on Lyapunov stability theory is provided to demonstrate that all signals in the closed-loop system are bounded, while the tracking error converges to a small neighborhood of zero. Finally, the proposed method is applied as an SLFM: the simulation results show that the presented controller has excellent control performance, the tracking error is less than 0.02 rad, and the tip polarization angle of the system does not exceed 0.045 rad. Additionally, the comparison with the recent DSC and SMC methods also shows that the designed controller behaves with less tracking error, which in return validates the effectiveness and superiority of the proposed control strategy. Full article

Submarine channels are critical conduits for sediment transport by turbidity currents, yet the quantitative influence of channel geometry on flow dynamics and sediment segregation remains poorly understood. Based on computational fluid dynamics, we constructed six three-dimensional numerical models of submarine channels with varying curvatures (R1–R3) and axial slopes (R4–R6) using ANSYS Fluent 17.2, with model settings informed by seafloor morphology from the South China Sea. The Eulerian–Eulerian multiphase model coupled with the standard k-ε turbulence model was used to simulate density fields, velocity structures, and sediment distributions. Results show that low-curvature channels exhibit symmetric density evolution and uniform sediment distribution, whereas high curvature induces pronounced asymmetry with a steep outer-bank density front and triggers secondary flow reversal. Increasing curvature also enhances flow thickness and radial mass flux. Increasing axial slope markedly elevates downstream velocity (0.09 to 0.16 m/s), reduces flow thickness, and shifts sediment distribution toward the inner bank without inducing secondary flow reversal. This study provides a parametric comparison of curvature versus slope effects on turbidity current dynamics and sedimentation patterns under fixed-bed, rectangular-channel assumptions. The findings offer a qualitative reference for interpreting sedimentary architectures in deep-water systems such as those in the South China Sea and analogous rift basins. Results are hypothesis-generating, pending further validation with field data and morphodynamic modeling. Full article

The minimal geometric deformation method is applied on Einstein–Maxwell field equations in this study to obtain two novel exact anisotropic solutions for polytropic configurations. A static spherically symmetric seed structure penetrated by the anisotropic fluid distribution is taken into consideration in order to accomplish this goal. The gravitational interaction of the new Lagrangian density is then coupled with the initial fluid configuration, representing an additional matter source. We obtain the field equations that correspond to the associated charged fluid sources. Two separate decoupled systems are developed when the field equations are subjected to a radial transformation. By applying the distinct constraints, each system’s solution is determined individually. The entire fluid configuration is then generated by combining these solutions via a certain linear combination. The constraints needed to determine the integration constants in the internal solutions are provided by junction conditions at the interface between the interior and exterior geometry. The suggested models are then verified by comparing them graphically under the observational data from the $CenX-3$ candidate star. In conclusion, for certain values of the decoupling parameter, our derived relativistic solutions satisfy established physical acceptability requirements. Full article

This work provides a theoretical/methodological contribution to the transient analysis of asymmetrical faults in three-phase systems. Transient analysis of three-phase systems is usually performed by resorting either to the instantaneous Symmetrical Component Transformation (SCT) or to numerical methods. In this paper, an analytical methodology based on the time-domain Clarke transformation is presented for the transient analysis of the most common asymmetrical faults. For each kind of asymmetrical fault, a specific circuit coupling between the Clarke αβ0 circuits is derived. Two main advantages are obtained over the SCT approach. First, the Clarke circuits involve real-valued voltages/currents, instead of complex variables as with the SCT. Second, the Clarke circuits αβ0 are not all coupled to each other. Therefore, the dynamic order of the Clarke equivalent circuits is lower than that of the SCT circuits. This property can be of interest in both the derivation of analytical and numerical solutions. A simple radial system is used to exemplify the proposed methodology. Full article

Scleral lenses (SLs) are increasingly incorporating complex optical designs, including front surface eccentricity (FSE) optimisation and wavefront-guided (WFG) corrections, to address residual higher-order aberrations (HOAs) in eyes with irregular corneas. Accurate in vitro optical verification of these surfaces relies on Hartmann–Shack (HS) metrology systems, yet commercially available devices differ substantially in lenslet array spatial sampling density, raising questions about their interchangeability for quality control purposes. This study evaluated the repeatability and inter-device agreement of HOA measurements in SLs obtained with two HS metrology systems with substantially different spatial sampling resolution. Sixteen SLs (four symmetric spherical, four spherical with toric periphery, four symmetric aspherical, four aspherical with toric periphery) were measured three times each using the SHSOphthalmic Cito (54 × 54 lenslet array) and SHSInspect Prio (157 × 157 lenslet array). Sphere (D) and Zernike coefficients from third to fifth radial orders were extracted for three aperture diameters (3.00, 5.00, and 7.00 mm) and analysed as root-mean-square (RMS) values by radial order and as Total HOA RMS. Both devices demonstrated excellent within-device repeatability for Sphere, RMS4, and Total HOA RMS (ICC: 0.994–1.000, CV ≤ 4%), while RMS3 and RMS5 showed moderate repeatability (ICC: 0.591–0.964, CV: 7–21%). Inter-device agreement was excellent at 5.00 and 7.00 mm (ICC: 0.950–1.000, mean bias < 0.006 μm), with a significant difference only for RMS3 at 7.00 mm aperture (p = 0.034). At 3.00 mm, significant systematic bias was detected for RMS4 (bias = −0.00102 μm, p < 0.001) and Total HOA RMS (bias = −0.00092 μm, p < 0.001), with the Cito underestimating values relative to the Prio. FSE design did not significantly influence inter-device differences. HS spatial sampling density influences HOA measurement accuracy in SLs at small apertures, and standardised high-resolution metrology protocols are essential to ensure accurate HOA characterisation. Full article

Capillary imbibition is the process by which liquids are absorbed into porous materials as a result of capillary pressure differences at the pore scale. Accurate characterization of imbibition dynamics, particularly in the presence of gravitational potential, is essential for understanding fluid transport in diverse systems such as soil, fractured rocks, filtration media, and plant roots. This study presents systematic imbibition experiments using filter papers with pore sizes of 2.5 µm, 11 µm, and 20 µm, each inclined at 80° to quantify the influence of gravitational potential on imbibition behavior. For horizontally positioned samples, the imbibition front propagated radially and symmetrically, exhibiting a power law dependence on time. The measured temporal exponents ranged from 0.386 to 0.403, consistently lower than the theoretical value of 1/2 predicted by the Lucas–Washburn law. With increasing permeability, the temporal exponent approached the Washburn limit, indicating a marked dependence of imbibition dynamics on pore structure. For the inclined configuration at an 80° angle, the imbibition fronts remained nearly circular but exhibited a pronounced displacement of the front center toward gravity. This displacement increased with permeability, from approximately 0.497 cm for the 11 µm filter paper to 3545 cm for the 20 µm filter paper, highlighting the combined effects of permeability and gravitational potential on fluid movement. Furthermore, the advance of the imbibition front was significantly slower in the smallest pores (2.5 µm) compared to the larger ones. Experimental results were evaluated against a theoretical model proposed by Medina, demonstrating moderate quantitative agreement at early times, when gravitational potential effects are less significant. These findings confirm that both the temporal scaling exponent and the spatial evolution of the imbibition front are governed by the porous medium’s permeability and inclination angle, providing experimental evidence of deviations from ideal Washburn behavior in real porous systems. Full article

This paper develops an analytical treatment of vibro-acoustic wave propagation in a cylindrical waveguide containing two clamped elastic membranes and a central flexible-shell segment. The acoustic field obeys the time-harmonic Helmholtz equation, the shell motion is described by Donnell–Mushtari thin-shell theory under axisymmetric loading, and the membrane response is governed by classical membrane theory and incorporated through a tailored Galerkin scheme. The resulting coupled fluid–structure boundary-value problem is solved by the Mode-Matching Method: the acoustic potentials are expanded in orthogonal radial eigenfunctions within each subregion, and continuity of pressure, normal velocity, and structural displacement are enforced at every interface. The mirror symmetry of the configuration is exploited by an exact decomposition into symmetric and anti-symmetric sub-problems, each of which reduces to a truncated linear algebraic system of dimension $4N+4$ for the unknown modal amplitudes. Acoustic power-balance identities provide a quantitative consistency check on the numerical implementation and diagnose convergence with respect to the truncation order; structural damping is accommodated through complex-modulus substitutions for the shell and the membrane tension without altering the algebraic structure of the system. The numerical results demonstrate that the dual-membrane configuration delivers transmission-loss values exceeding $25\mathrm{dB}$ across the low-frequency band relevant to HVAC and automotive applications, with a representative plateau near $13\mathrm{dB}$ at the reference geometry, through resonance-driven modal coupling between the acoustic field and the compliant interfaces. Parametric studies identify the excitation frequency, the inner-membrane radius, the shell radius, and the chamber length as effective design parameters for tuning the attenuation. The formulation furnishes a unified and computationally efficient analytical tool for predicting and optimising noise attenuation in flexibly coupled cylindrical duct systems. Full article

Transient analyses of liquid-fueled molten salt reactors involve strong coupling among neutronics, delayed neutron precursor transport, thermal–hydraulics, and solid heat transfer, leading to high computational costs for repeated high-fidelity simulations. To enable fast multi-physics prediction at unseen operating conditions, a parametric non-intrusive reduced-order model (ROM) combining proper orthogonal decomposition (POD) and higher-order dynamic mode decomposition (HODMD) is developed. Coupled full-order snapshots generated from an OpenFOAM-based one-eighth symmetric core model based on a simplified MSRE benchmark configuration are used to construct reduced representations for 11 physical fields. The POD truncation rank, HODMD delay dimension, and interpolation model are selected using leave-one-out cross-validation, with polynomial, radial basis function, and Gaussian process regression models considered as interpolation candidates. For unseen parameter points, the model maintains high accuracy in both the interpolation stage and the temporal extrapolation stage. In the temporal extrapolation stage, the highest mean relative $L_2$ error for the inlet-temperature-step case is $2.112\%$, whereas all mean relative $L_2$ errors for the inlet-velocity-step case remain below $0.177\%$. The results indicate that, under the present cases and parameter settings, the proposed framework provides an accurate and rapid surrogate for multi-physics transient prediction. Full article

Auxetic cellular materials attract increasing attention for crashworthiness and impact protection due to their negative Poisson’s ratio (NPR). However, conventional double-arrowhead auxetic honeycombs (DAHs) with straight ligaments often exhibit limited energy absorption and unstable collapse under large deformation. In this study, a curvilinear hybrid auxetic honeycomb (CHAH) is proposed by replacing straight walls with smoothly curved ligaments and embedding a circular positive Poisson’s ratio subcell to provide symmetric support. The mechanical behavior of the CHAH is investigated through a combined experimental–numerical approach. Finite element simulations are validated by quasi-static compression experiments, and a parametric study is conducted to evaluate the influence of key geometric variables on specific energy absorption (SEA) and peak crushing force (PCF). Based on the validated simulations, a multi-objective optimization framework integrating optimal Latin hypercube sampling, radial basis function surrogate modeling, and NSGA-II is employed to optimize the structural parameters. Compared with the conventional DAH under identical material and volume conditions, the CHAH exhibits significantly improved deformation stability and energy absorption capability, with SEA increasing by up to 67.06% and a more stable plateau response. In addition, SEA and PCF can be effectively tuned by varying the geometric angles (θ₁, θ₂). Full article