Search Results (188)

HPMC, regulating slurry properties, is widely used in cement-based materials. Research on the application of HPMC in gangue slurry is still in its early stages. Moreover, the interactive effects of various factors on gangue slurry performance have not been thoroughly investigated. The work examined the effects of slurry concentration (X₁), maximum gangue particle size (X₂), and HPMC dosage (X₃) on slurry performance using response surface methodology (RSM). The microstructure of the slurry was characterized via scanning electron microscopy (SEM) and polarized light microscopy (PLM), while low-field nuclear magnetic resonance (LF-NMR) was employed to analyze water distribution. Additionally, industrial field tests were conducted. The results are presented below. (1) X₁ and X₃ exhibited a negative correlation with layering degree and slump flow, while X₂ showed a positive correlation. Slurry concentration had the greatest impact on slurry performance, followed by maximum particle size and HPMC dosage. HPMC significantly improved slurry stability, imposing the minimum negative influence on fluidity. Interaction terms X₁X₂ and X₁X₃ significantly affected layering degree and slump flow, while X₂X₃ significantly affected layering degree instead of slump flow. (2) Derived from the RSM, the statistical models for layering degree and slump flow define the optimal slurry mix proportions. The gangue gradation index ranged from 0.40 to 0.428, with different gradations requiring specific slurry concentration and HPMC dosages. (3) HPMC promoted the formation of a 3D floc network structure of fine particles through adsorption-bridging effects. The spatial supporting effect of the floc network inhibited the sedimentation of coarse particles, which enhanced the stability of the slurry. Meanwhile, HPMC only converted a small amount of free water into floc water, which had a minimal impact on fluidity. HPMC addition achieved the synergistic optimization of slurry stability and fluidity. (4) Field industrial trials confirmed that HPMC-optimized gangue slurry demonstrated significant improvements in both stability and flowability. The optimized slurry achieved blockage-free pipeline transportation, with a maximum spreading radius exceeding 60 m in the goaf and a maximum single-borehole backfilling volume of 2200 m³. Full article

We investigate a two-dimensional system of active Brownian dumbbells using molecular dynamics simulations. In this model, each dumbbell is driven by an active force oriented perpendicular to the axis connecting its two constituent beads. We characterize the resulting phase behavior and find that, across all values of activity, the system undergoes phase separation between dilute and dense phases. The dense phase exhibits hexatic order, and for large enough activity, we observe a marked increase in local polarization, with dumbbells predominantly oriented towards the interior of the clusters. Compared to the case of axially self-propelled dumbbells, we find that the binodal region is enlarged towards lower densities at all activities. This shift arises because dumbbells with transverse propulsion can more easily form stable cluster cores, serving as nucleation seeds, and show a highly suppressed escaping rate from the cluster boundary. Finally, we observe that clusters exhibit spontaneous rotation, with the modulus of the angular velocity scaling as $\omega \sim r_g^{-2}$, where $r_g$ is the cluster’s radius of gyration. This contrasts with axially propelled dumbbells, where the scaling follows $\omega \sim r_g^{-1}$. We develop a simplified analytical model to rationalize this scaling behavior. Full article

The isotopic shift of the bound-electron g factor in highly charged ions (HCI) provides a sensitive probe for testing physics beyond the Standard Model, particularly through interactions mediated by a hypothetical scalar boson. In this study, we analyze the sensitivity of this method within the Higgs portal framework, focusing on the uncertainties introduced by quantum electrodynamics corrections, including finite nuclear size, nuclear recoil, and nuclear polarization effects. All calculations are performed for the ground-state $1s$ configuration of hydrogen-like HCI, where theoretical predictions are most accurate. Using selected isotope pairs (e.g., ${\mathrm{He}}^{4/6}$, ${\mathrm{Ne}}^{20/22}$, ${\mathrm{Ca}}^{40/48}$, ${\mathrm{Sn}}^{120/132}$, ${\mathrm{Th}}^{230/232}$), we demonstrate that the dominant source of uncertainty arises from finite nuclear size corrections, which currently limit the precision of new physics searches. Our results indicate that the sensitivity of this method decreases with increasing atomic number. These findings highlight the necessity of improved nuclear radius measurements and the development of alternative approaches, such as the special differences method, to enable virtually the detection of fifth-force interactions. Full article

In recent years, UAV formations have garnered significant attention in fields such as reconnaissance, communications, and transportation. This paper aims to design an efficient passive localization method for UAV formations that satisfies system electromagnetic compatibility (EMC) requirements. A self-adjustment model characterized by internally active communication and externally silent operation for UAV formations is proposed, which optimizes the positions of the UAVs under test based on their current locations and standard reference positions while adhering to formation geometry constraints. By comprehensively considering constraints including the number of UAVs, formation geometry, and system EMC, this study evaluates electromagnetic radiation interference within the UAV formation system and derives an iterative adjustment scheme for formation positions. Finally, simulation experiments through specific case studies calculate polar radius deviations and polar angle deviations during the adjustment process. The results validate that the proposed method meets the requirements for both formation adjustment and EMC, thereby providing a more scientific basis for passive localization and position adjustment in UAV formations. Full article

Symmetrical bearing raceway led to the axial sliding of rolling elements, which is a crucial factor in shortening the operational lifespan. This study addresses this limitation through three-step advancements: first, a parametric equation for logarithmic spiral raceways is developed by analyzing their asymmetric geometric features; second, based on the geometrical model, we systematically investigate the parameters of the logarithmic spiral that affects the bearing performance metrics; and finally, a novel fatigue life prediction framework that integrates static mechanical analysis with raceway parameters establishes the theoretical foundation for optimizing the raceway parameters. The results of the model analysis show that the error of the maximum contact stress verified by the finite element method is less than 8.3%, which verifies the model’s accuracy. Increasing the contact angle α of the outer ring from 82 to 85 can increase fatigue life by 15.6 times while increasing the initial polar radius O of the inner ring from 7.8 mm to 8.1 mm will cause fatigue life to drop by 86.9%. The orthogonal experiment shows that the contact angle α of the outer ring has the most significant influence on the service life, and the optimal parameter combination (clearance δ of 0.02 mm, inner race and outer race strike angles α of 85°, an inner race initial polar radius $r_o$ of 7.8 mm, and an outer race initial polar radius $r_o$ of 7.9 mm) achieves a 60.7% fatigue life increase. The findings provide theoretical support and parameter guidance for the optimal bearing design with logarithmic spiral raceways. Full article

In this study, the microstructure and electrochemical and passive characteristics of NiCr_25.2−xMoAl_x (x = 0, 1.25, 2.5, and 5 mol.%) alloys were investigated. The results show that Ni-Cr-Mo-Al alloys with varying Cr:Al ratios both had a single FCC structure without any second structure precipitates, and decreases in dislocation density and grain size were observed as the Al content in NiCrMoAl alloys increased. It was found from the electrochemical results that the NiCr_23.95MoAl_1.25 alloys had the maximum radius for a semicircle and the lowest I_corr, indicating an enhanced anti-corrosion performance (R_ct: 8.08 ± 0.368 × 10⁵ Ω cm², I_corr: 1.05 ± 0.003 × 10⁻⁷ A/cm²). In this study, it was found that the anti-corrosion performance of the alloys had an approximate connection to the composition and density of passive films. Denser and more stable microstructures in NiCr_23.95MoAl_1.25 alloys were further proven by potentiostatic polarization tests and Mott–Schottky experiments, showing a lower stable current density and acceptor density (N_A: 9.79 ± 0.4 × 10⁻²⁰ cm⁻³). In addition, the results of XPS show that the Al_1.25 specimen had the highest Cr₂O₃ in the passive film’s content among the NiCrMoAl alloys. Cr₂O₃ was the main component, suggesting an enhanced protective influence of passive film. The present study can offer guidance for the application of nickel-based alloys with high anti-corrosion resistance in marine environments. Full article

Highly (0002)-oriented Al_1−xSc_xN thin films with different Sc doping concentrations (x = 0, 0.2, 0.25, 0.3, and 0.43) were prepared via a magnetron sputtering system. The effects of Sc doping on the crystal structure and electrical property of the as-prepared thin films were investigated experimentally. The results of synchrotron radiation grazing-incidence wide-angle X-ray scattering (GIWAXS) and X-ray diffraction (XRD) demonstrated that the Sc³⁺ substitution for Al³⁺ induced asymmetric lattice distortion: the a-axis exhibited monotonic expansion (reaching 3.46 Å at x = 0.43) due to the larger atomic radius of Sc (~0.87 Å), while the c-axis attained a maximum value of 5.14 Å at x = 0.2 and subsequently contracted as the bond angle reduction became dominant. The dielectric constant increased to 34.67 (225% enhancement) at x = 0.43, attributed to the enhanced polarization of Sc-N bonds and interfacial charge accumulation effects. Simultaneously, the dielectric loss increased from 0.15% (x = 0) to 6.7% (x = 0.43). Leakage current studies revealed that high Sc doping (x = 0.43) elevated the leakage current density to 10⁻⁶ A/cm² under an electric field of 0.2 MV/cm, accompanied by a transition from Ohmic conduction to space-charge-limited current (SCLC) at a low electric field strength (<0.072 MV/cm). Full article

This study innovatively presents a hollow-core anti-resonant fiber integrating double-tube nesting and a single-layer anti-resonant wall. Featuring an exclusive two-layer cladding configuration along with an outer cladding circular ring, it differs significantly from traditional fibers. After careful parameter optimization, at 1.55 μm wavelength, the fiber shows excellent performance. Its confinement loss drops to 0.00088 dB/km, 1–2 orders lower than traditional ones. The proportion between the loss of the lowest higher-order mode and that of the fundamental mode reaches 19,900, indicating excellent single-mode performance. In the case of a bending radius of 11–14.2 cm, the x-polarization loss is below 0.001 dB/km, showing good bending resistance. Through structural comparisons, this paper quantitatively reveals the effects of the anti-resonant wall, cladding tube, and outer cladding ring on fiber performance. From the practical fiber-drawing process, it thoroughly analyzes the impact of the outer connecting tube’s offset angle on fiber performance. This research provides crucial theoretical support for new hollow-core fiber design, manufacture, and application, and is expected to drive technological innovation in this field. Full article

Under the framework of classical electrodynamics, this article investigates the nonlinear Thomson scattering generated by the cross-collision between a tightly focused linearly polarized Gaussian laser pulse and a relativistic electron through numerical simulation and emulation. The oscillation direction and emission angle of the electron’s trajectory are influenced by the beam waist radius and the delay time. The spatial radiation distribution of electrons exhibits a comet-shaped pattern, with the radiation being concentrated in the forward position. This is attributed to the high laser intensity at the focus, resulting in intense electron motion. As the beam waist radius keeps increasing continuously, the maximum radiation polar angle in the spatial distribution decreases. The time spectrum exhibits a symmetrical three-peak structure, with a high secondary peak. Meanwhile, the supercontinuum spectrum gradually transforms into a multi-peak distribution spectrum. In the multi-peak mode, the main peak and the secondary peak will interchange during the increase in the waist radius, generating rays with higher frequencies and energies. The aforementioned research findings reveal a portion of the mechanism of the nonlinear Thomson scattering theory and are beneficial for generating X-rays of higher quality. Full article

Photoacoustic imaging (PAI) has rapidly developed in biomedical imaging. The point spread function (PSF) is critical for addressing image blurring in PAI. However, in circular integrating detection systems, the PSF exhibits spatial variations. This makes PSF extraction challenging. The existing studies typically assume that the PSF is known or obtained through experiments. This study proposes a method for extracting the PSF based on the polar coordinate system. By transforming the image from the Cartesian coordinate system to the polar coordinate system, the “spin blur” problem is decomposed into multiple independent subproblems. With the separation of the radial and angular directions, the blurring kernel remains invariant at each radius, thereby simplifying the estimation of the PSF. To estimate the blurring kernel, we use polynomial algebraic common factor extraction techniques. The numerical simulation results validate the effectiveness of the method, and the impact of sample size on computational efficiency and accuracy is discussed. Full article

Marine Cold Air Outbreaks (MCAOs) are critical drivers of high-latitude climates because they regulate the exchange of heat, moisture, and momentum between cold continental or polar air masses and relatively warmer ocean surfaces. In this study, we combined CloudSat–CALIPSO observations (2007–2017) with ERA5 reanalysis data to investigate the microphysical properties and vertical structure of snowfall during MCAOs. By classifying events using a low-level instability parameter, we provide a detailed comparison of the vertical and spatial characteristics of different snowfall regimes, focusing on key cloud properties such as the effective radius, particle concentration, and ice water content. Our analysis identified two distinct snowfall regimes: shallow stratocumulus-dominated snowfall, prevalent during typical MCAOs and characterized by cloud top heights below 3 km and a comparatively lower ice water content (IWC), and deeper snowfall occurring during non-CAO conditions. We demonstrate that, despite their lower instantaneous snowfall rates, CAO-related snowfall events cumulatively contribute significantly to the total ice mass production in the subpolar North Atlantic. Additionally, CAO events are characterized by a greater number of ice particles near the surface, which are also smaller ($r_{\mathrm{eff}}$ of 59 μm versus 62 μm) than those associated with non-CAO events. These microphysical differences impact cloud optical properties, influencing the surface radiative balance. Full article

In this paper, we investigate the classical Axelrod model of cultural dissemination under an adaptive network framework. Unlike the original model, we place agents on a complex network, where they cut connections with any agent that does not share at least one cultural trait. This rewiring process alters the network topology, and key parameters—such as the number of traits, the neighborhood search range, and the degree-based preferential attachment exponent—also influence the distribution of cultural traits. Unlike conventional Axelrod models, our approach introduces a dynamic network structure where the rewiring mechanism allows agents to actively modify their social connections based on cultural similarity. This adaptation leads to network fragmentation or consolidation depending on the interaction among model parameters, offering a framework to study cultural homogeneity and diversity. The results show that, while long-range reconnections can promote more homogeneous clusters in certain conditions, variations in the local search radius and preferential attachment can lead to rich and sometimes counterintuitive dynamics. Extensive simulations demonstrate that this adaptive mechanism can either increase or decrease cultural diversity, depending on the interplay of network structure and cultural dissemination parameters. These findings have practical implications for understanding opinion dynamics and cultural polarization in social networks, particularly in digital environments where rewiring mechanisms are analogous to recommendation systems or user-driven connection adjustments. Full article

The interaction of a Gaussian vortex beam (GVB) with metamaterials during its propagation is of significant interest to the optical community. These GVBs are classified as structured light beams that possess orbital angular momentum (OAM). Understanding the behavior of structured light beams is essential for clarifying fundamental interaction mechanisms with metamaterial structures. So, this work delves into the investigation of the propagation characteristics of a GVB within a chiral material. The analytical expressions for GVB propagating through a chiral medium are obtained by using the extended Huygens–Fresnel diffraction integral formula and the optical ABCD matrix system. In a chiral medium, GVB exhibits a tendency to fragment into a left circularly polarized (LCP) beam and a right circularly polarized (RCP) beam, each following its unique propagation paths. The beam intensity and gradient force are computed and discussed for OAM mode number, beam waist radius, and chirality parameter. This research will be quite helpful for light manipulation, optical sorting, optical radiation force, the radiative transfer process, and optical guiding. Full article

This study examines the microstructure and corrosion resistance of FeCrNiAl_0.7Cu_0.3Si_x (x = 0, 0.1, 0.3, and 0.5) high-entropy alloys (HEAs) in a 3.5% NaCl solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and electrochemical testing were employed to systematically analyze the alloys’ microstructures and corrosion behavior. The XRD results indicate that the addition of Si affects the phase structure of the alloy. At Si = 0, the alloy exhibits a single BCC phase. By increasing the Si content to 0.1 and 0.3, a BCC₂ phase appears. At Si = 0.5, Si-containing intermetallic compounds form. SEM observations reveal that as the Si content increases, the alloy develops a distinct dendritic structure. Polarization tests in the 3.5% NaCl solution show that the corrosion current density first decreases and then increases with increasing Si content. At Si contents of 0.1, 0.3, and 0.5, the corrosion current densities are 4.275 × 10⁻⁶ A·cm⁻², 4.841 × 10⁻⁷ A·cm⁻², and 2.137 × 10⁻⁶ A·cm⁻², respectively. FeCrNiAl_0.7Cu_0.3S_0.3 HEA exhibits the lowest corrosion current density, indicating a lower corrosion rate. Electrochemical impedance spectroscopy (EIS) tests show that at Si = 0.3, the alloy has the largest capacitive arc radius. The charge-transfer resistance (RCT) for the alloys with the Si contents of 0.1, 0.3, and 0.5 are 2.532 × 10⁵ Ω·cm², 4.088 × 10⁵ Ω·cm², 4.484 × 10⁵ Ω·cm², and 2.083 × 10⁵ Ω·cm², respectively. FeCrNiAl_0.7Cu_0.3Si_0.3 HEA has the highest RCT, which indicates a more stable passivation film and better resistance to chloride ion intrusion. The corrosion morphology observed after polarization testing shows that all alloys exhibit intergranular corrosion characteristics. The Si content alters the distribution of passivation film-forming elements, Cr and Ni. Compared to other alloys, the corrosion morphology of FeCrNiAl_0.7Cu_0.3Si_0.3 HEA is more complete. Combining the polarization, EIS, and corrosion morphology results, it can be concluded that FeCrNiAl_0.7Cu_0.3Si_0.3 HEA exhibits the best corrosion resistance in the 3.5% NaCl solution. Full article

The growing population and the impacts of climate change present a major challenge to forests, which play a crucial role in regulating the carbon cycle. Pakistan, as a Kyoto Protocol signatory, has implemented afforestation initiatives such as the Khyber Pakhtunkhwa (KP) government’s Billion Tree Afforestation Project (BTAP). Quantifying the environmental impacts of such initiatives is very important; however, carbon pool data for BTAP plantation regions remain unavailable and are underexplored. This study aims to quantify aboveground biomass (AGB) and carbon sequestration potential (CSP) in the BTAP plantation regions using remote sensing and field data. Random sampling of 310 circular plots (17.84 m radius) provided measurements for tree height and diameter, from which AGB was calculated using allometric equations. Remote sensing data from Sentinel-1 and Sentinel-2, combined with polarization rasters and vegetation indices, were used to train and evaluate multiple regression models including multiple linear regression (MLR), support vector regression (SVR), and random forest regression (RFR). The RFR model outperformed the others (R² = 0.766) when using combined optical and radar data, yielding a mean AGB of 4.77 t/ha, carbon stock of 2.24 t/ha, and CO₂ equivalent of 10.36 t/ha. For BTAP plantations, the total biomass reached 1.19 million tons, with 2.06 million tons of CO₂ equivalent sequestered, corresponding to an annual sequestration of 0.47 tC/ha/yr and a potential of 99.18 ± 15 tC/ha. This research introduces innovative predictive models and a comprehensive carbon assessment framework for afforestation projects, providing critical insights for policymakers and climate change mitigation efforts. Full article