Search Results (378)

Nutating mills offer intense comminution dynamics without the gravitational constraints of conventional tumbling mills; however, their structural response and charge–structure interaction mechanisms remain insufficiently characterized. This work examines the dynamic behavior of a laboratory-scale nutating mill (NuMill) with granular charge through combined experimental characterization and a two-way coupled numerical framework integrating multi-body dynamics (MBD) with the discrete element method (DEM). This study expands on previous work, extending the characterization of the NuMill to include mount stiffness, damping, and charge–structure coupling. The NuMill was adapted with vibration isolation mounts and internal chamber ribs to more closely emulate the operating behavior of industrial Hicom mills. Measurements of forces, torques, and accelerations were obtained across a range of mounting, charge, and chamber geometry configurations. Results show that approximating the granular charge in a ribbed chamber as a rigid body leads to substantial predictive error, overestimating crank-pin forces by 21% and underestimating driveshaft torque by 82% at 700 RPM. Incorporating experimentally characterized stiffness into the coupled MBD–DEM model showed good prediction accuracy for granular charge at 700 RPM. The simulation overestimated crank-pin force by 34%, underestimated driveshaft torque by 25%, and reproduced rigid-body natural frequencies within 1%. These findings demonstrate that structural compliance and charge–structure coupling play a central role in determining operational loads in nutating mills. The validated modeling framework developed here provides a more reliable basis for design assessment and parameter selection in industrial nutating milling applications and extends existing experimental foundations for laboratory-scale systems. Full article

Merging galaxy clusters represent one of the most powerful macroscopic laboratories in the Universe for searching for new physics within the dark sector. High-velocity cosmic collisions inherently separate the dark matter and stellar components from the highly collisional, X-ray-emitting intracluster gas. These massive systems provide an ideal environment to probe the fundamental nature of dark matter, specifically testing whether it behaves as a strictly collisionless particle or exhibits non-zero self-interactions. While pioneering systems like the Bullet Cluster historically demonstrated the macroscopic decoupling of dark and ordinary matter, the field has evolved into a sophisticated discipline driven by multi-disciplinary methodologies. This review synthesizes recent theoretical and empirical advances in interpreting post-collision dynamics. It examines how the synergy of combined approaches—integrating multi-wavelength observations from gravitational lensing and X-ray mapping with high-fidelity N-body hydrodynamical simulations—allows the translation of macroscopic spatial observables into stringent constraints on microscopic particle properties. Through this synthesis, the work evaluates how leveraging heterogeneous merger ensembles can reliably advance the ongoing search for physics beyond the standard cosmological model. Full article

We investigate null geodesics, photon spheres and black hole shadows for the static spherically symmetric non-Schwarzschild black hole solution of Einstein–Weyl gravity, a higher-derivative extension of General Relativity containing a quadratic Weyl-curvature term. Such higher-curvature theories are motivated by attempts to formulate a quantum theory of gravity, where they improve the ultraviolet behaviour of the gravitational interaction, and also arise naturally as effective descriptions in approaches such as string theory. We employ the numerical black hole solution obtained by Lü et al. to compute the photon sphere, the shadow radius and the angular size of the shadow as observed by static observers. We show that, for black holes of equal mass, the photon sphere, shadow radius and angular size are consistently larger than those of the corresponding Schwarzschild black hole, with the deviations increasing monotonically with the higher-curvature coupling parameter $\alpha$. Motivated by the Event Horizon Telescope observations of M87* and Sagittarius A*, we further compare the predicted shadow size with current observational uncertainties and derive phenomenological upper bounds on the dimensionless coupling $\alpha /m^2$. These results demonstrate that black hole shadow observations provide a promising avenue for testing Einstein–Weyl gravity and constraining quantum-motivated higher-curvature corrections to General Relativity. Full article

This study addresses the critical need for accurate and efficient large-scale urban fire spread path prediction in dense urban areas by proposing a new gravitational framework-based theory. Its core innovation is the “characteristic attractive force” model, which mechanistically quantifies fire spread as a dynamic interaction between buildings, integrating factors like spacing, height, area and density effects to predict trajectories from the initially ignited building. This study adopts a GIS-based rapid prediction framework that circumvents the dependence on complex physical parameters. It utilizes high-precision spatial data and optimized algorithms to streamline prediction processes while retaining favorable prediction accuracy. Validated on two real-world clusters, the proposed approach enables effective visualization of dynamic propagation trajectories and pathway spectra that characterize the detailed propagation routes and ignition sequences. Notably, the framework achieves exceptional efficiency, completing predictions for large clusters in tens of seconds per scenario, making it suitable for real-time risk assessment. Overall, this work advances urban fire modeling with an innovative, efficient, and practical tool to support fire safety engineering and emergency management decision-making. Full article

In this paper, we investigated the capability of Yukawa gravity to explain the Schwarzschild precession of S-stars as a probe for General Relativity and to map the allowed parameter space of a potential fifth force. We simulated the S38 star orbit in a Yukawa gravity model and fitted it into the observed astronomical data of the S38 star using the Markov Chain Monte Carlo method in order to constrain the parameters (strength $\delta$ and range $\lambda$) of the Yukawa interaction. Comparing these findings with previous results for the S2 star reveals that the best-fit values for $\lambda$ are remarkably close, while the magnitudes of $\delta$ are slightly smaller for S38. These results map the joint statistical boundaries of a fifth force at the Galactic Center. Although the General Relativity limit ($\delta =0$) falls well within the reported $1\sigma$ uncertainties, rendering potential nominal deviations statistically insignificant, the interaction range $\lambda$ exhibits a highly stable spatial scale across different stellar orbits. This cross-consistency between independent datasets, with stable clusters near 360, 1900, and 7000 AU, keeps a viable physical window open for a fifth force. This agreement demonstrates that the interaction scale is robust against individual single-orbit systematic errors, ensuring that this parameter domain remains a prime target for future high-precision astrometric observations. Ultimately, analyzing S-star kinematics within Yukawa gravity provides a powerful independent tool for testing General Relativity and bounding non-standard gravitational effects at the Galactic Center. Full article

Facial aging is a multifactorial process characterized by progressive structural and functional changes involving skin, soft tissues, muscles, and skeletal support. Current conceptual models primarily rely on static anatomical descriptions and regional assessment scales that evaluate visible signs such as wrinkles, folds, and volume loss. Although these approaches provide useful clinical reference points, they may only partially capture the dynamic interactions between muscular activity, tissue aging, and gravitational forces that shape facial morphology over time. In this article, we propose a conceptual framework for interpreting facial aging based on the vectorial dynamics generated by facial mimic muscles. Within this perspective, facial muscles can be considered sources of contraction vectors that exert mechanical influences on facial tissues throughout life. Under physiological conditions, facial appearance reflects a dynamic equilibrium between opposing vectorial influences. However, progressive tissue weakening combined with repetitive muscular activity may gradually alter this balance. This hypothesis-generating, vector-based model integrates muscular dynamics with tissue aging and gravitational effects to offer a complementary interpretative framework for facial aging. It is not intended as a validated biomechanical theory, but rather as a conceptual tool to stimulate further anatomical, imaging-based, and clinical investigation. Full article

We introduce a new method of dimensional analysis based on complete systems of units, such as the metric and Planck systems, in which fundamental dimensionless constants arise naturally. In fact, it is the reformulated Planck system that communicates its dimensionless constants to the metric or any other system. The method reveals additional complex dynamical scales and physical effects beyond those amenable to conventional dimensional analysis. We formulate our strategy in simple settings involving pairs of seemingly unrelated constants, and then we extend the analysis to more complicated cases involving combinations of three to five well-known universal constants. In constructions involving several unrelated constants, the method captures increasingly complex effects and places two or more disparate physics areas into a single framework connecting them by never-before-seen combinations of fundamental dimensionless constants, such as the fine-structure constant and the gravitational coupling constant. Thus, this method provides a pathway to blending descriptions of two or more fundamental interactions that have so far eluded a consistent theoretical formulation. Full article

Acoustically levitated thin reflective plates provide a promising approach for contactless optical beam steering by eliminating mechanical hinges, sliding interfaces, and the associated wear and friction losses. However, unlike conventional spherical particles or droplets, thin planar reflectors exhibit highly geometry-dependent acoustic force distributions and are highly susceptible to lateral drift and angular destabilization when the acoustic field is dynamically reconfigured for beam steering. Here, we present a theoretical and simulation-based stability analysis of an acoustically levitated thin reflective plate driven by a phase-controlled dual-array acoustic field. A reduced-order model based on the Gor’kov potential is developed to characterize the acoustic potential landscape, escape-barrier depth, and local restoring stiffness during phase-gradient-induced mirror tilting. The simulations reveal that increasing the phase gradient progressively distorts the trapping potential and reduces the available trapping stability margin. Among the translational degrees of freedom, the lateral restoring stiffness deteriorates much more rapidly than the axial stiffness, indicating that lateral slippage is the primary instability pathway during continuous steering. Parametric analysis further shows that thinner mirrors with larger radii can improve trapping stability by increasing the effective acoustic interaction area while reducing gravitational and inertial penalties. The influence of non-ideal acoustic driving conditions is also evaluated to determine practical operating limits for stable operation. These results clarify the stability mechanisms governing acoustically suspended planar reflectors and provide theoretical design guidelines for robust contactless optical beam-steering systems. Full article

The European crafts ecosystem faces critical structural threats, declining practitioner numbers, weakening intergenerational transmission, limited digital literacy, and competition from industrial imitation. Existing online craft communities are narrowly material-specific and structurally ill-suited to the cross-disciplinary dialogue required for systemic sector transformation. This paper presents the design, iterative development, and pilot evaluation of the Craeft Community, a multi-stakeholder Virtual Community of Practice (VCoP) developed within the Horizon Europe CRAEFT project. Three research questions guided the study: how a multi-stakeholder VCoP should be structured to overcome disciplinary fragmentation; to what extent a stewarded digital forum can operationalize Situated Learning and Communities of Practice theory; and what factors facilitate or inhibit engagement and post-funding sustainability. Using design-based research, the platform evolved through four iterative phases, culminating in restructuring from a material-based architecture into five transversal thematic pillars, driven by survey evidence from 151 European craft professionals and systematic stakeholder feedback. The pilot phase yielded 86 registered members, 31 posts, and 27 interactions, with Transmission & Training as the most engaged pillar. Qualitative analysis reveals substantive cross-disciplinary discourse alongside a structural Effort-Engagement Gap, a persistent tension between forum participation demands and the gravitational pull of mainstream social media. The study demonstrates that a thematically organized, stewarded VCoP can meaningfully operationalize apprenticeship-based learning in digital settings, advancing craft heritage preservation, economic resilience, and hybrid professional identity formation at the intersection of craft and technology. Full article

CO₂ flooding plays a crucial role in enhancing oil recovery (EOR) in heterogeneous reservoirs; however, the reservoir’s vertical rhythmic characteristics and permeability gradients significantly influence the flooding efficiency. Unlike homogeneous reservoirs, CO₂ migration in heterogeneous reservoirs is jointly controlled by gravitational overburden and differences in flow conditions, which can easily lead to gas short-circuiting and the formation of dominant flow paths, thereby reducing the degree of crude oil mobilization. However, systematic research on the mechanisms of CO₂ flooding under different rhythm types and permeability difference remains relatively scarce. In this study, two-dimensional large-scale physical model experiments were conducted using stratified core plates with a planar size of 30 × 30 cm² and a single-layer thickness of 1 cm. The experiments were performed at 70 °C and 18 MPa, corresponding to the target reservoir conditions, with CO₂ injected from the inlet side and outlet pressure controlled by a backpressure valve. Under these conditions, CO₂ remained in the supercritical state during displacement. These experiments were designed to comparatively investigate the effects of reservoir rhythm and permeability contrast on pressure distribution, CO₂ migration patterns, and crude oil mobilization. The study elucidated the mechanisms by which reservoir heterogeneity influences the effectiveness of CO₂ flooding. The results show that the positive rhythmic unit delays upward CO₂ migration and gas breakthrough because of the low-permeability top layer, resulting in the highest ultimate oil recovery of 73.35%. In contrast, the reverse rhythmic unit promotes rapid CO₂ breakthrough through the high-permeability top layer and forms dominant flow paths, causing insufficient mobilization of the middle and bottom layers and yielding the lowest oil recovery of 51.03%. In the sandwich-type rhythmic unit (low–high–low permeability configuration), the interaction between the high-permeability middle layer and gravity override enhances mobilization in the top and middle layers, whereas oil mobilization in the bottom layer remains limited. Under interlayer conditions, increasing the permeability contrast from three-fold to five-fold strengthens preferential flow in the high-permeability layer and reduces oil recovery from 65.58% to 60.99%. 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

We put forward the idea that in addition to invariance under coordinate transformations of general relativity (GR) the gravitational interaction is invariant under arbitrary scale deformations of the metric field, as well as other fields. In addition, we assume that the scaling field has an internal symmetry. Because scale invariance is imposed only on gravity, while the standard model (SM) retains its usual non-Weyl-invariant form, the full framework is not merely a rewriting of GR plus the SM. The global charges that are associated with the internal symmetry could potentially source the gravitational field. Throughout, the framework is treated as a classical generalization of GR on sufficiently sub-Planckian energies; accordingly, any discussion of global charges is to be understood within this effective classical domain. In the case that isotropic deformations are considered, the theory reduces to a Weyl-invariant scalar–tensor (WIST) version of GR. In case that the reference metric is chosen to be Minkowski, the metric factorization takes the standard vierbein form, apart from the additional internal structure assumed here. A few other implications of WIST are considered as well. Full article

We present a spectral-action framework for connecting generalized trace dynamics (GTD) to the structural form of the low-energy action of the observed Universe. The fundamental single-STM-atom Lagrangian is decomposed exactly into a purely bosonic sector, boson–fermion cross terms, and bifermionic terms. This sectorwise decomposition furnishes a dictionary to almost-commutative spectral geometry: the bosonic sector supplies a quadratic GTD Dirac functional built from the six split-biquaternionic differential directions together with octonionic vector/gauge fluctuations; the cross-sector supplies, under an explicit localization hypothesis, a sesquilinear fermionic pairing; and the bifermionic sector supplies the scalar/internal channel that is bosonized into the Higgs bridge field. We also record the principal-symbol link between the $\mathrm{SO}(3,3)$ BF variables and the four-dimensional leafwise Dirac operator. The two four-dimensional leaves of the six-dimensional base overlap in two common directions; from the observed (gravitational) leaf, the two nonintersecting directions of the complementary leaf are internal, so the second leaf is reinterpreted as the weak-interaction sector rather than as an independent spacetime—a reinterpretation stated here as an explicit hypothesis. Under stated assumptions—spontaneous localization, Euclidean continuation, six- to four-dimensional BF reduction, and a candidate observed-leaf finite geometry compatible with the $E_6/J_3\left({\mathbb{O}}_{\mathbb{C}}\right)$ inputs—the bosonic heat-kernel expansion yields the structural low-energy classes of terms: Einstein–Hilbert gravity, Yang–Mills kinetic terms, and scalar kinetic and potential terms. In addition, we provide a candidate finite spectral triple with explicit finite trace invariants, verify that the localization map respects the one-generation lepton/quark representation split, identify visible color-singlet scalar channels with electroweak quantum numbers $(\mathbf{1},\mathbf{2},\pm 1/2)$, and exhibit a smooth regulator family with explicit cutoff moments $(f_0,f_2,f_4)$. Conversely, the assembled low-energy spectral action admits a natural inverse bilinear lift back to split bioctonionic trace dynamics. Every arrow of the construction is classified as an exact algebraic identity, an imported result, a working hypothesis, or an open problem. Under this classification, the paper offers a possible architecture for obtaining low-energy gauge–gravity physics from GTD, with conditional consistency checks and reductions; it is not a completed first-principles derivation of the Standard Model coupled to gravity. Full article

The multi-messenger exploration of dark matter and physics beyond the Standard Model has emerged as a central direction in modern astro-particle physics, particularly following the discovery of gravitational waves. In this work, we present a comprehensive review and forward-looking perspective on machine-learning-enhanced multi-messenger approaches, combining information from gravitational waves, cosmic rays, gamma rays, neutrinos, and collider experiments. We summarize the current state of the field, discuss recent methodological developments, and outline a coherent research program aimed at integrating heterogeneous datasets within a unified inference framework. We collaboratively propose a plan for forthcoming analyses aiming at extracting information on the properties and interactions of dark matter, and finally on its genesis, combining multi-messenger astronomy techniques and inputs from laboratory physics. The main objectives planned in this line of research comprise: (i) the multi-messenger analysis of new physics in cosmology, including mainly, but not only, several different models of dark matter; (ii) the phenomenology of new physics signatures in ground-based cosmic rays experiments, with cross-correlation to the corresponding physical, astrophysical and cosmological observations; (iii) the development of machine learning methods for data analysis in ground-based cosmic rays experiments, in light of the new physics signatures. We note that several groups have explored the use of multi-messenger observations, including gravitational waves, to probe alternative dark matter candidates. The present work builds on these developments by focusing on the role of machine learning in integrating heterogeneous datasets. We foresee that a cross-fertilizing approach combining the information that arises from very different experimental methodologies will represent the right and successful path to extract information about the very elusive dark matter particles and provide answers to the main questions that are left in fundamental physics. Full article

Rotational energy harvesters are often constrained by narrow operating bandwidths and sensitivity to specific rotational regimes, limiting their effectiveness under variable-speed conditions. This work presents an orientation-adaptive dual-mode piezoelectric rotational energy harvester capable of broadband energy extraction across diverse rotational and vibration environments. The proposed design combines gravity-induced magnetic excitation at low rotational speeds with centripetal-force-induced nonlinear dynamics at higher rotational speeds, enabling passive transition between operating modes without active tuning. A coupled nonlinear electromechanical model is developed to investigate the interactions among gravitational forcing, magnetic coupling, centripetal loading and piezoelectric transduction. Numerical simulations reveal the transition from gravity-dominated mono-stable behaviour to broadband nonlinear operation as rotational speed increases. Experimental validation is conducted using representative vibration profiles from aerospace, automotive, civil infrastructure and industrial environments. The results demonstrate clear orientation-dependent performance, with the downward cantilever configuration achieving a maximum average power output of 57.8 μW under aerospace elevation excitation, whilst the upward configuration exhibits improved robustness under broadband random vibrations. The proposed orientation-adaptive framework provides a compact, stator-independent solution for broadband rotational energy harvesting under realistic operating conditions. Full article