Search Results (237)

This study examined the effect of east–west orientation of willow tree (Salix alba L.) rows on soil biological activity and weed dynamics in a temperate maize (Zea mays L.) intercropped agroforestry (AF) system in Eastern Hungary. The experiment evaluated how the year (2022, 2023), location (distance from the rows), and irrigation (IR) influenced spatial patterns of earthworm (EW) parameters and weed cover. The study aimed to assess how willow-based AF systems influence soil biological and weed community dynamics under varying IR and row spacing, in comparison with monoculture cropland (MC) systems, and to evaluate their potential role in climate change adaptation in arable farming. Both soil sampling for the EW survey and vegetation studies were conducted along perpendicular transects extending from the tree rows to measure EW abundance and biomass, as well as total weed cover. Experimental results revealed clear spatial gradients in EW distribution and weed abundance near the tree rows, driven by litter input, shading, moisture, and reduced disturbance. These effects were intensified under IR at narrower row spacings. No significant differences were observed between AF-South (shaded), AF-Center, and MC plots; however, significantly higher EW abundance and biomass were found on the AF-North (sunny) side. As for the location, significantly greater total EW abundance was found at AF-North (105.0 individual m⁻²) compared with the MC plots. AF systems enhance soil biological activity and shape weed dynamics through spatial ecological gradients influenced by tree row spacing and irrigation, supporting their role as sustainable land-use systems while emphasizing the need for site-specific management and further long-term optimization. Full article

Hysteretic nonlinear vibration systems can exhibit jumps, coexisting attractors, and strong dependence on the initial state, particularly when material hysteresis is coupled with geometric nonlinearity. This paper investigates the global nonlinear dynamics of a harmonically forced single-degree-of-freedom oscillator incorporating pseudoelastic shape memory alloy (SMA) wires in a perpendicular geometric configuration. Cyclic force–displacement tests on pseudoelastic SMA wires are used to calibrate the constitutive response, after which steady-state dynamics are analyzed using time integration, numerical continuation (COCO), and basin-of-attraction computations over representative excitation frequencies, pre-tension levels, and the number of wires. The calibrated model predicts rich response regimes including jump phenomena, coexisting stable solutions, multistability, asymmetric periodic responses, and the pronounced dependence of the achieved steady response on initial conditions and internal state. Basin computations reveal sensitive partitioning of the state space between competing attractors, highlighting the influence of the initial and internal state in oscillators that combine pseudoelastic hysteresis with geometric stiffening. Additional numerical exploration of a negative pre-tension extension indicates transitions to more complex responses, including quasi-periodic and chaotic behaviour, but these are presented as secondary results outside the directly validated tension-wire regime. The results clarify how calibrated SMA hysteresis and geometric nonlinearity jointly shape multistability and basin structure in pseudoelastic oscillators. Full article

Geometric relation parsing is a prerequisite for automated geometry problem solving, especially when diagram interpretation depends jointly on visual appearance and textual conditions. In this study, we examine a text-conditioned parsing setting derived from PGDP5K and propose a lightweight parser with atomic cue extraction, iterative visual–semantic feedback, and differentiable logic regularization. Because the active high-level labels are derived through a rule-based weak-supervision protocol, the results should be interpreted as parser-level evidence under Ext-PGDP5K rather than proof of general geometric semantic understanding. The nominal label space contains five candidate relations, while the current evaluation focuses on four active relations with positive instances: Intersect, Parallel, Perpendicular, and Bisect. Compared with text-only, image-only, global-fusion, and shuffled-text controls, the proposed parser improves Edge-F1 and Macro-F1, with the clearest gains for Parallel and Perpendicular. Ablations show that the atomic probe is the main source of improvement, while logic regularization and feedback exhibit non-monotonic interactions. Although limited by weak labels, lexical cues, and the absence of downstream solver validation, this study provides a reproducible protocol-aligned testbed for analyzing text-conditioned relation prediction and low-order logic regularization in geometric diagram parsing. Full article

A numerical investigation of forced convection heat transfer in a three-dimensional T-shaped bifurcating channel with an upstream rotating cylinder and a downstream vibrating wavy wall is presented. The working fluid is a ternary hybrid nanofluid (Fe₂O₃, CuO, MoS₂ in water) exhibiting Casson rheology under an inclined magnetic field. The novelty of this work lies in the first integrated configuration combining these simultaneous mechanical, magnetic, and non-Newtonian effects. Using COMSOL Multiphysics, 413 parametric combinations of Reynolds number, Hartmann number, Casson parameter, nanoparticle shape and volume fraction, magnetic field angle, cylinder rotation speed, wall amplitude (Am), and period were solved. Average Nusselt and Bejan numbers quantified heat transfer enhancement and thermodynamic irreversibility. To interpret the high-dimensional parameter space and to circumvent the prohibitive computational cost of additional 3D magnetohydrodynamics simulations, machine learning (XGBoost) models were developed to rank feature importance and provide fast, accurate surrogate predictions (R² > 0.99). Cylinder rotation dominates heat transfer, increasing the Nusselt number by over 980% (feature importance 0.42) with a modest entropy penalty. Nanoparticle volume fraction reduces the Nusselt number via viscous damping. Magnetic field parameters negligibly affect heat transfer but strongly influence entropy generation; a perpendicular field recovers up to 97% thermal efficiency at high Hartmann numbers. Full article

Automated data exploration is very useful for evaluating key aspects of populations such as young adults (which here refers to the youth population in the United States represented by students in grades 9 through 12). This article shows how Principal Component Analysis (PCA) can be used for this exploration. PCA is applicable to data analysis situations with data from $n$ individuals of $m$ attributes (generally $n >> m$). For analytical purposes, the data can be visualized as $n$ points in a Euclidean space with Cartesian coordinates, with $m$ perpendicular coordinate axes, where each axis corresponds to an attribute. When $m$ is large, the points become difficult to visualize, so PCA is useful, as it is a dimensionality reduction method that facilitates the visualization of the points. The objective of this article is to identify relationships between attributes, where there is a primary attribute of interest. The present work describes some of the main theoretical aspects of PCA and then uses PCA to analyze data, as a practical example. The data comes from the publicly available results of a 2023 survey administered to a nationally representative sample of students in the United States, to assess health risk behaviors among young adults (students in grades 9 through 12), which was conducted by the Youth Risk Behavior Surveillance System (YRBSS), managed by the Centers for Disease Control and Prevention—CDC. The results of this work graphically discover relationships between specific data attributes. The reliability of the results is then discussed, considering: (1) recommendations taken from PCA literature, and (2) the use of a graphical tool called a Zoning Biplot, an improved form of displaying PCA results. This work is relevant because it uses the Zoning Biplot, proposed by the authors, which shows more detail in the results compared to a conventional Biplot; the authors argue that this detail allows for valid results across a larger number of datasets, such as the dataset in the example presented. The authors present a graphical development to support the concept and advantage of a Zoning Biplot. Full article

We find novel confined states in the spin-S nearest-neighbor antiferromagnetic Heisenberg model on the two-dimensional Penrose lattice. Linear spin waves have massively degenerate eigenstates strictly confined to tricoordinated sites. They contrast with the well-known itinerant analogs in the tight-binding model, where electrons are confined but extended to both tricoordinated and pentacoordinated sites. It is the site potentials in the spin-wave Hamiltonian, originating from Coulomb interactions between electrons, that confine spin waves to minimally coordinated sites only. Confined states in the tight-binding Hamiltonian consist of six types of building blocks, whereas those in the spin-wave Hamiltonian consist of only four of them. Confined spin waves are robust against 1/S corrections. Emergent O(S⁰) interactions further confine—superconfine—spin waves into two separate groups within tricoordinated sites. Full article

The quantum motion of a photon in an arbitrary medium was considered within the framework of the gauge symmetry group $SU\left(2\right)\otimes U\left(1\right)$ using the Yang–Mills (Y-M) equations for Abelian fields. A system of second-order partial differential equations (PDEs) for the vector wave function of a photon is derived using the first-order Y-M equations as identities. The full wave function of a photon was defined as the arithmetic mean of the components of the wave function. In a particular case, an equation is obtained for its full wave function, taking into account the structure of space-time in a plane perpendicular to the direction of propagation of the photon. The quantum state of a photon in a nanowaveguide was investigated, and it is shown that under certain conditions, it is reduced to the problem of two coupled 1D quantum harmonic oscillators (QHO) with variable frequencies. An explicit expression is obtained for the wave function of a photon, which is characterized by two vibrational quantum numbers. A quantum theory of a photon for a dissipative medium has been developed taking into account the processes of absorption and emission of photons. The mathematical expectation (ME) of the photon wave function is constructed as the product of two 2D integral representations in which the integrand is the solution of a system of two coupled second-order PDEs. The ME of the probability amplitude of the transition of a single-photon state into one of the two-photon entangled Bell states is constructed. Finally, it was proven that, in addition to frequency, spin, momentum and polarization, the photon also has a spatial structure responsible for the cross sections of processes in which this massless fundamental particle participates. Full article

In this paper, the circular Sitnikov three-body problem is studied under the combined influence of radiation pressure and albedo. The model consists of two equal-mass primaries moving in circular orbits about their center of mass and an infinitesimal body constrained to oscillate along the perpendicular axis. The radiative emission from one primary and the reflected radiation from the other are incorporated into the effective potential through radiation and reflectivity parameters. Using the Jacobi integral, we determine the energetically admissible region for vertical motion and examine how radiative effects modify the accessible phase space. The study shows that the system admits a single vertical equilibrium point at the origin, which remains linearly stable within the physically admissible parameter range. Radiation and albedo reduce the effective restoring force and increase the oscillation period, producing a measurable rescaling of the physical time without altering the geometrical structure of the phase trajectories. The phase-space dynamics are further explored by means of Poincare (first-return) maps obtained from numerical integration of the nonlinear equation of motion. The resulting invariant curves confirm that the motion remains regular and bounded, while their progressive contraction reflects the reduction in the oscillation amplitude with increasing radiative effects. Overall, the results show that albedo acts as a quantitative modifier of the vertical Sitnikov dynamics by changing the effective potential, the admissible energy domain, and the observable time scale, without generating new qualitative phase-space structures. Full article

In order to ensure the smooth and safe advancement of mining faces through abandoned roadways (ARs), this study investigates the backfilling process in a mining operation in western China, where abandoned roadways continuously appear ahead of newly arranged mining faces. A theoretical analysis of the immediate roof of the roadway is conducted, leading to the conclusion that the optimal spacing between backfilling bodies is 8 m. Numerical simulation software is used to examine the effects of different backfilling body lengths—6 m, 8 m, and 10 m—on the stress state, deformation characteristics, and stress distribution of the surrounding rock during mining. Based on the simulation results, appropriate backfilling body lengths are selected: 8 m for ARs perpendicular to the mining face and 10 m for ARs parallel to the mining face. The proposed backfilling process is validated through industrial tests, demonstrating its effectiveness in ensuring mining safety and improving economic efficiency. Full article

This study evaluated eleven resin cements used as core build-up materials by examining the following properties: (a) push-out force between root dentin and the fiber post; (b) pull-out force between the fiber post and the core build-up material; (c) shear bond strength of the resin cement to root dentin; (d) flexural strength of the resin cement; and (e) flexural modulus of elasticity of the resin cement. The purpose of this investigation was to clarify the relationships between recently available universal adhesives, core build-up materials, resin cements, and fiber posts. All experiments were performed at two evaluation periods: after 1 day of water storage (Base) and after 20,000 thermocycles (TC 20k). For the push-out test, simulated post spaces were prepared in single-rooted human premolars. The specimens were sectioned perpendicular to the long axis into 2 mm-thick slices and then subjected to push-out testing to assess the bond strength of the dentin–resin cement–fiber post complex. No significant differences in bonding performance were found between Base and TC 20k. These findings suggest that universal adhesives used for pretreatment of multiple substrates in fiber post cementation can provide not only strong but also durable adhesion over time. Full article

We investigated the dynamics of molecular reorientation in freely suspended smectic liquid–crystal films (FSLCFs) under the influence of heat flux. We also examined how external thermal gradients affect molecular alignment in these ultra-thin films. FSLCFs were fabricated in a temperature-controlled chamber in this study. When heat flux was applied perpendicular to the film plane, rotation of line defects, known as 2π walls, was observed. This rotation resulted from thermomechanical torque acting on the molecular director, a phenomenon referred to as the Lehmann effect. By analyzing the changes in defect evolution, how heat flux drives the self-organization of liquid–crystal structures can be understood. In this study, we combined experimental observations and computational simulations to model and interpret the results. The results enhance the understanding of the underlying mechanisms governing molecular reorientation and defect dynamics in FSLCFs, particularly in non-equilibrium conditions, to study this mechanism in the microgravity environment. The results also contribute to the development of advanced liquid–crystal technologies, with potential applications in energy-efficient devices, adaptive materials, and space technology systems. Full article

The properties of a Ca₉La(VO₄)₇ single crystal were studied using dielectric spectroscopy and second-harmonic generation. The crystal structure of Ca₉La(VO₄)₇ grown using the Czochralski technique was refined using single-crystal data. The distribution of Ca²⁺ and La³⁺ cations over structural positions was determined. The crystal structure refinement results were compared with those obtained previously from powder X-ray diffraction data. It was shown that the refinement carried out using two different data sets leads to approximately the same results for the distances in the polyhedra, but their distortion is significantly less in the case of using single-crystal data for calculation. Dielectric properties and conductivity measurements were performed on polished single-crystal wafers cut parallel and perpendicular to the c axis. Second-harmonic generation and dielectric temperature measurements revealed the presence of a reversible ferroelectric first-order phase transition at about 1224 K from the ferroelectric β-phase (space group R3c) to the paraelectric β′-phase. The ferroelectric–paraelectric phase transition is accompanied by a complex structural rearrangement, including a 60° rotation of the V1O₄ tetrahedron, as well as slight displacements of the Ca²⁺ and La³⁺ cations. It has been shown that the conductivity differs only slightly along the polar axis and perpendicular to it. Above the phase transition temperature, the activation energy of the conductivity is the same for all directions, E_a~1.2 eV. The influence of composition on the phase transition temperature and the formation of ferroelectric and nonlinear optical properties is discussed. Full article

Addressing the dual challenges of efficient water resource utilization and high construction costs in agricultural production, this study proposes a low-cost sprinkler irrigation system featuring a joint optimized design of water supply facilities and sprinkler layout. Initially, to mitigate water wastage at the field boundaries, an enhanced sprinkler layout is designed. This design strategically adjusts sprinkler spacing to position units along the irrigation area’s perimeter, leveraging their adjustable spray angles for semicircular coverage, thereby achieving superior water conservation compared to traditional honeycomb full coverage layouts. Subsequently, considering the non-linear relationship between pipeline cost and its length and flow rate, a supply network comprising five independent pipelines running perpendicular to the river is constructed. Furthermore, water storage tanks are strategically located at the head of each pipeline near the water source to reduce costs. Finally, constrained by the daily soil moisture levels required for crop survival, an inference-based dimension reduction algorithm is employed to jointly optimize the daily pipeline flow rate and storage tank capacity for each supply line. Specifically, by constructing the functional mapping between flow rate and tank capacity, the complex bivariate optimization problem is reduced to a single-variable extremum problem. Additionally, a calculation method for the feasible region of decision variables is proposed to ensure solution validity. The results demonstrate that the proposed scheme achieves a minimum total construction cost of CNY 2,611,404.00 with a total storage tank capacity of 114,892.40 L, and generates a detailed daily irrigation strategy. This study offers a significant model reference and a technical pathway for developing agricultural irrigation systems that are both economical and efficient. Full article

Vertical wind shear plays a crucial role in the organization and persistence of mesoscale convective systems, yet its geometrical and topological effects remain challenging to quantify. In this study, we introduce a shear-induced anisotropic metric, denoted $d_S$, which embeds the direction and magnitude of environmental wind shear directly into the framework of persistent homology. The metric deforms the ambient geometry by weighting distances differently along and across the shear direction, enabling topological descriptors to respond dynamically to the flow environment. We establish the analytical properties of $d_S$, and demonstrate its compatibility with Vietoris–Rips filtrations. The method is applied to the Corsican bow–echo event of 18 August 2022, where shear vectors are derived from ERA5 reanalysis data. Two complementary topological analyses are performed: a transport analysis on $H_0$ using Wasserstein distances, and a structural analysis on $H_1$ persistent generators under parallel and perpendicular shear metrics. The results reveal distinct topological evolutions associated with different shear orientations, highlighting the sensitivity of persistent homology to shear-induced deformation. Overall, the framework provides a mathematically consistent bridge between dynamical meteorology and topological data analysis, extending persistent homology to anisotropic metric spaces. Full article

To address the computational-efficiency bottlenecks of Hybrid A* and its bidirectional variant in long-distance parking and narrow-slot scenarios, an improved bidirectional Hybrid A* algorithm is presented. First, the cohesion cost is reformulated in a vector-space representation. Distance and heading-consistency terms are evaluated using dot products, which eliminates trigonometric operations and reduces the overhead of node evaluation. Second, an RS (Reeds–Shepp) cost template is constructed on a sparse grid of key nodes. Neighborhood costs are approximated with Euclidean-distance correction. In addition, a geometry reachability-based trigger is designed for analytic RS connections to avoid redundant analytic linking and unnecessary RS curve computations. Third, a KD-tree spatial index is introduced to accelerate nearest-neighbor queries in the Voronoi potential field, and vehicle corner coordinates are updated in a vectorized manner to improve the efficiency of potential-field evaluation. Simulation results in parallel and perpendicular parking show that, compared with the baseline bidirectional Hybrid A* algorithm, RS computations are reduced by 98.7% and 97.8%, respectively, while total planning time is shortened by 63.2% and 57.5%, with stable path quality. These results indicate that the proposed method effectively mitigates the dominant computational costs of bidirectional Hybrid A* in complex parking tasks and improves the efficiency and real-time performance of automatic parking path planning. Full article