Search Results (5,313)

The assessment of tunnel blasting effects traditionally relies on manual inspection and contact measurements, which are subjective, inefficient, and lack comprehensive quantification. To address this, this study proposes a novel closed-loop framework that integrates multi-view 3D reconstruction with intelligent recognition for quantitative blasting evaluation and parameter optimization. Rather than claiming novelty in these basic computer vision algorithms, the novelty of this work lies in their tunnel blasting oriented integration: reconstructed geometry is converted into blasting relevant indicators and then linked to parameter adjustment decisions within a closed-loop workflow. The framework begins with a standardized image acquisition workflow designed for challenging tunnel environments (e.g., dust, uneven light), followed by image enhancement using histogram equalization and bilateral filtering. A key improvement is an enhanced SIFT feature matching strategy, which incorporates a BBF optimized K-D tree and RANSAC to achieve robust correspondence establishment on texture-repetitive rock surfaces. This enables the generation of high-precision 3D models of the tunnel face via Structure from Motion (SfM) and Poisson surface reconstruction. From these models, quantitative indices are automatically extracted: rock mass structural planes are clustered via the ISODATA algorithm, structural traces are delineated using a minimum cost path method, and face flatness is evaluated through curvature analysis. These indices form the basis for intelligent blasting assessment. Crucially, the assessment results are directly fed back to optimize blasting parameters (e.g., adding cut holes, adjusting auxiliary hole spacing). Field application in the Huangtai Tunnel demonstrated that this closed-loop framework significantly improved face flatness (achieving over 50% improvement in the high-curvature area ratio) and contour control. Further verification in the Donghongshan Tunnel showed that the proportion of the sharp feature region decreased from 20.3% to 7.9% after optimization. The proposed framework transitions blasting management from empirical judgment to a data driven, intelligent optimization process, offering a scalable solution for enhancing quality and efficiency in tunnel construction. Full article

This paper presents a flexible conformal beam-scanning leaky-wave antenna (LWA) array based on a PI-ABS composite substrate and spoof surface plasmon polariton (SSPP) structure for Ku-band (12–18 GHz) applications. The proposed design features periodically symmetric gradient linear metallic stubs and interleaved tapered radiating patches to realize efficient SSPP slow-wave transmission, −1st spatial harmonic radiation, and open-stopband (OSB) suppression simultaneously. Benefiting from the flexible PI-ABS composite structure, the antenna maintains stable radiation performance under different curvatures, overcoming the mechanical instability and beam-scanning sensitivity of conventional flexible LWAs. The four-element conformal array achieves continuous beam scanning from −67° to 32° with a peak gain of 16.5 dBi and radiation efficiency above 58% across the entire band. Both simulation and measurement results validate that the proposed design integrates flexible conformality, wideband beam scanning, and high radiation efficiency, providing a novel solution for conformal wireless communication systems. Full article

This paper presents a high-sensitivity and anti-interference optical intensity differential curvature sensor based on seven-core fiber (SCF), and its performance is verified through simulation. The sensor adopts a “single-mode fiber–tapered SCF” structure, using the light intensity ratio between the peripheral core and the central core for curvature demodulation. It enhances the sensitivity while effectively suppressing common-mode interference. The simulation results show that when the cone zone diameter of the tapered SCF is optimized to 30 µm, the mode coupling between the cores is significant, forming a strongly coupled super-mode transmission system. Based on the intensity differential principle, this sensor achieves excellent linear response within the curvature range of 0–10 m⁻¹, with a sensitivity of −0.145/m⁻¹. The sensor has a compact structure and simple fabrication process, providing new ideas and solutions to break through the technical bottlenecks of existing fiber curvature sensors, and has broad application prospects in engineering monitoring fields. Full article

We find restrictions on a trans-Sasakian structure $\left(F,\mathbf{u},\gamma ,\alpha ,\beta \right)$ on a 3-dimensional Riemannian manifold $\left(M^3,g\right)$ so that $\left(M^3,g\right)$ is homothetic to a Sasakian manifold. In that, first we show that if the vector $\mathbf{u}$ of the trans-Sasakian structure $\left(F,\mathbf{u},\gamma ,\alpha ,\beta \right)$ on a 3-dimensional Riemannian manifold $\left(M^3,g\right)$ is an affine conformal vector with affine potential $\alpha \ne 0$ and the condition $\mathbf{u}\left(\alpha \right)=-{\beta }^2$ holds, necessarily implies $\left(M^3,g\right)$ is homothetic to a Sasakian manifold. Similarly, it is shown that if the vector $\mathbf{u}$ of the trans-Sasakian structure $\left(F,\mathbf{u},\gamma ,\alpha ,\beta \right)$ on a 3-dimensional Riemannian manifold $\left(M^3,g\right)$ is a projective vector and the sectional curvatures of the plane sections containing $\mathbf{u}$ are positive constant, then $\left(M^3,g\right)$ is homothetic to a Sasakian manifold. Finally, we find certain generic conditions on a 3-dimensional Riemannian manifold $\left(M^3,g\right)$ possessing a trans-Sasakian structure $\left(F,\mathbf{u},\gamma ,\alpha ,\beta \right)$ so that $\left(M^3,g\right)$ is homothetic to a Sasakian manifold. Full article

Vertical axis wind turbines (VAWTs) have regained attention for distributed, urban, and floating offshore applications, yet the literature remains fragmented across competing rotor concepts and modelling traditions. This review consolidates the principal archetypes—Savonius, H-Darrieus, troposkein Darrieus, helical Darrieus, and Savonius–Darrieus hybrids—through five governing parameters: drag-versus-lift-driven operating principle, tip speed ratio $\mathsf{\lambda }=\mathsf{\omega }\mathrm{R}/{\mathrm{V}}_{\infty }$ (0.6–1.2 for Savonius; 2.5–5.0 for Darrieus), solidity $\mathsf{\sigma }=\mathrm{N}\mathrm{c}/\mathrm{R}$ (0.1–0.4), chord-based Reynolds number ${\mathrm{R}}_{\mathrm{e}\_\mathrm{c}}$ (${10}^5–{10}^6$), and peak power coefficient ${\mathrm{C}}_{\mathrm{p}\_\mathrm{m}\mathrm{a}\mathrm{x}}$ (0.15–0.25 for Savonius; 0.35–0.45 for optimized H-Darrieus). Off-design performance is dominated by unsteady mechanisms that quasi-steady streamtube models cannot resolve—leading edge vortex shedding, dynamic stall hysteresis, blade–wake interaction, and flow-curvature-induced virtual camber—each examined for its contribution to the instantaneous torque ${\mathrm{C}}_{\mathrm{T}}\left(\mathsf{\theta }\right)$ and the cycle-averaged ${\mathrm{C}}_{\mathrm{p}}$. Turbulence closures are benchmarked against phase-locked PIV and torque measurements: $\mathrm{k}–\mathsf{\omega }\mathrm{S}\mathrm{S}\mathrm{T}$ URANS captures peak-region ${\mathrm{C}}_{\mathrm{p}}$ to within $\pm 5–10\%$ but over-predicts torque below ${\mathsf{\lambda }}_{\mathrm{o}\mathrm{p}\mathrm{t}}$; the $\mathsf{\gamma }–{\mathrm{R}}_{\mathrm{e}\_\mathsf{\theta }}$ transition SST model reduces this error to $\pm 3–5\%$; DES, DDES, and LES reach $\pm 2–3\%$ at one to two orders of magnitude higher cost. Best practice computational fluid dynamics (CFD) guidelines are consolidated: domain extents of 15D upstream, 10D downstream, and 20D lateral; rotating sub-domain ${\mathrm{D}}_{\mathrm{r}\mathrm{o}\mathrm{t}}$ $\approx 1.5\mathrm{D}$; ${\mathrm{y}}^{+}\le 1$; $\Delta \mathsf{\theta }\le 0.1°$; and 20–30 revolutions before sampling. Performance enhancement strategies (variable pitch, guide vanes, helical twist, and hybridization) are reviewed quantitatively, with reported ${\mathrm{C}}_{\mathrm{p}}$ gains of $5–30\%$. Four research priorities are identified: (i) transition-sensitive turbulence closures validated below ${\mathrm{R}}_{\mathrm{e}\_\mathrm{c}}$ = $5\times {10}^5$; (ii) coupled aero-hydro-servo-elastic models for floating offshore VAWTs; (iii) machine-learning-augmented turbulence modelling—including physics-informed neural networks (PINNs) and neural-network-corrected RANS closures—to improve unsteady flow prediction at sub-LES cost; and (iv) integrated aeroacoustic–aeroelastic frameworks for urban and building-integrated deployment. Full article

This paper studies an inspection path-planning task for cross-domain platforms, in which a Reeds–Shepp unmanned surface vehicle (USV) must plan the shortest curvature-constrained path from the starting configuration (e.g., the USV depot) to the intermediate inspection point and then to the terminal configuration (e.g., the technical facility). The problem emerges from cooperative inspection applications and can be formulated as a three-point Reeds–Shepp problem (3PRSP), where the heading at the intermediate point needs to be optimized. To the best of our knowledge, neither closed-form nor optimization-based solutions exist for this problem. We propose an approximation-and-optimization-based approach that approximates the trigonometric constraints arising from the Reeds–Shepp forward–backward motion kinematics using piecewise-linear formulations, enabling the resulting model to be effectively solved by mathematical programming solvers. Extensive simulations and comparisons with the three-point Dubins approach and related methods demonstrate the accuracy and computational efficiency of the proposed method. Full article

In this article, some remarkable results on general relativistic spacetimes with non-constant scalar curvature $\tau$, admitting almost Ricci-Bourguignon solitons and gradient almost Ricci-Bourguignon solitons, have been established. Finally, a non-trivial example of a general relativistic spacetime is constructed by using partial differential equations to validate some of our findings. Full article

We develop an operational, measurement-first framework for the geometry of locally finite cell complexes, in which length is defined as a count of face crossings, and curvature is read off from the discrepancy between a measured radius and a radius reconstructed from boundary, area, or volume counts using the same yardstick. We prove that the count metric is geodesic on every locally finite complex, and we introduce a unified small-ball/small-sphere curvature estimator that is valid in dimensions two through four with a single closed-form expression. By comparison with the standard small-ball volume expansion of a smooth conformal metric $g=e^{2u}{g}_0$, we establish a quantitative identification theorem with explicit rate $O(a/r+r)$, which optimizes to $O\left(\sqrt{a}\right)$ at $r\asymp \sqrt{a}$. We extend the construction to directional (sectional) estimators via Fermi tubes around geodesic two-slices, assemble the curvature operator, Ricci tensor, and scalar curvature in three dimensions, and prove a measured Gromov–Hausdorff convergence theorem for the rescaled count metric. All hypotheses are verified explicitly on Voronoi complexes of conformal metrics. Throughout, we are explicit that the discrete construction is interpreted via, and its asymptotic validity is established by comparison with, the smooth Riemannian theory; the contribution is the unified counts-only protocol with rigorous convergence rates, not a reformulation of curvature itself. Full article

In this study, the 33.5 J low-velocity impact (LVI) behaviour of unidirectional T300/5208 CFRP cylindrical shell panels with a 40-ply [45/0/−45/90]_5s layup was investigated using Abaqus/Explicit under the effect of the curvature-height parameter (f = 0–62.5 mm; a₁–a₆). To address the limitation of the previous single-block approach in not being able to represent delamination, the study was carried out on two models: an intralaminar-only (SC8R single-block) model and an intralaminar + interlaminar model containing nine cohesive interfaces. Quantitative results: In the intralaminar-only model, the maximum contact force peaks at a₃ (f = 25 mm), with 13,192 N, representing a 13.7% increase relative to the flat panel; whereas in the intralaminar + interlaminar model, the force is highest at a₂ (f = 12.5 mm), with 14663 N, and decreases monotonically with curvature (10,765 N at a₆). Failure mechanism: In the intralaminar-only model, the dominant intralaminar mode is matrix tensile damage (DAMAGEMT); in the intralaminar + interlaminar model, interlaminar separation (CSDMG) governs the total damage, and the initiated delamination area reaches its minimum at a₄ (f = 37.5 mm), with 7282 mm², and its maximum at a₅, with 9821 mm². Thus, a curvature-dependent delamination-minimum regime arises that differs from the a₃ optimum of the intralaminar-only model. An impact performance index (DPI) and its surface-area-corrected derivative, DPI* = DPI/ζ, were applied separately for both models. It was shown that delamination systematically lowers the performance level and shifts the optimum curvature window. All findings are comparative trends within a single numerical framework. Full article

Graph-based fraud detection in multi-relational social networks must capture heterogeneous relation semantics and diverse fraud patterns while preserving geometric consistency and remaining scalable. Existing methods often either force all relations into a shared Euclidean or single-curvature space, or fuse relation-wise embeddings after mapping them to tangent coordinates, which weakens curvature-dependent metric information. We propose Relation-Specific Curvature Fields on Product Manifolds (RSCF-PM), a geometry-consistent framework that learns relation-specific curvature and represents each node as a tuple on a Riemannian product manifold. Each relation is encoded in its own hyperbolic space, and cross-relation fusion is performed directly through the product metric rather than Euclidean concatenation. On top of this representation, we introduce a multi-prototype classifier to model multiple fraud modes within each class. To support large-scale training, we adopt tangent-space aggregation as an efficient approximation to the Fréchet mean. Experiments on four public fraud detection benchmarks, including the 5.78M-node T-Social network, show that RSCF-PM achieves the best results on T-Social, FDCompCN, and YelpChi, while remaining highly competitive on Amazon, with up to 4.96% AUC improvement over strong baselines. Ablation and efficiency studies further confirm the complementary value of each component and the practical scalability of the framework. Full article

Spain’s extensive marine jurisdiction—comprising a continental shelf of approximately 100,000 km² and an Exclusive Economic Zone approaching one million km²—requires robust geospatial frameworks to support ecosystem assessment and marine policy implementation. This study presents GIS-based methodologies developed by the Spanish Oceanographic Institute (IEO-CSIC) within national initiatives such as LIFE IP INTEMARES project and the implementation of Marine Strategy Framework Directive (European Directive 2008/56/EC). The geospatial workflows developed for these initiatives integrates heterogeneous spatial datasets—such as multibeam bathymetry, acoustic backscatter, Remote Operated Vehicle (ROV) and towed-camera transects, sediment samples, oceanographic profiles, and species-habitat occurrence records—into a unified spatial analysis environment. Applied methods include digital terrain modeling, derivation of geomorphometric indices (e.g., slope, rugosity, curvature), image classification, and spatial statistics to quantify habitat extent, condition, and anthropogenic pressures. An integrated spatial analysis framework combining environmental and anthropogenic data is used to support zoning and management decisions within Marine Protected Areas (MPAs). Additionally, the deployment of WebGIS platforms facilitates data dissemination, iterative review, and stakeholder engagement, thereby enhancing transparency and accessibility. The resulting high-resolution maps, harmonized datasets, and computed spatial indicators—aligned with Marine Strategy Framework Directive (MSFD) descriptors such as habitat distribution (D1C4–C5) and seafloor integrity (D6C2–C3)—demonstrate how GIScience methods provide reproducible, decision-ready information to support the monitoring and management of Spain’s diverse marine ecosystems. Full article

This study investigates the traction response and operational risk of a compact ball-frame and tensioned-steel-cable drag-reduction system for submarine cable pulling inside HDD steel casings, based on local full-scale experiments. Thirteen test cases were designed by considering pipe curvature, device spacing, terminal reaction-force loading mode, and dry or sand–slurry in-casing conditions. In addition to the equivalent friction coefficient, three response descriptors, namely, the average traction force, peak coefficient, and fluctuation coefficient, were introduced to evaluate mean resistance, peak amplification, and process stability. The results show that pipe curvature significantly amplifies both traction peaks and response fluctuations, and should therefore be regarded as a key factor governing operational risk. The effect of device spacing is environment-dependent: under dry conditions, a moderate reduction in spacing improves rolling continuity, whereas under sand–slurry conditions, excessively dense deployment may aggravate local obstruction and response fluctuation. Stronger terminal reaction-force loading also increases peak amplification and instability. Based on these findings, a case-specific and experiment-oriented framework for operational-risk classification is proposed. The present results are intended to support traction-response characterization, device arrangement, and construction control under representative local conditions, rather than to replace full-scale field validation. Full article

Drought severely limits maize yields. Water–saving irrigation methods like partial root–zone drying (PRD) can improve water use efficiency (WUE) but often result in variable yield responses among genotypes. We hypothesized that differences in root hydrotropism might contribute to some of this variability. Seven maize varieties were evaluated for hydrotropic response in a controlled moisture–gradient assay and then grown for five weeks under fixed PRD versus full irrigation in a greenhouse. The different maize varieties exhibited distinct hydrotropic behaviors: roots of V6 and V7 bent toward water much faster and more strongly, while V2 responded slowly with minimal curvature. Under PRD, genotypes also differed in root distribution and shoot performance. However, hydrotropism alone did not guarantee good shoot maintenance. One strongly hydrotropic genotype (V7) still suffered a large biomass reduction under PRD. Overall, genotypes that maintained better shoot water status, along with larger stem diameter and higher shoot water content, achieved the highest WUE under PRD. These results indicate that root hydrotropism varies widely in maize varieties. This variation was associated with shoot traits and WUE under PRD, suggesting that the benefit of hydrotropism for drought adaptation may depend on complementary shoot characteristics. Breeding for drought–resilient maize may therefore require combining strong root hydrotropism with the ability to maintain shoot function under water deficit. Full article

Objective: To evaluate the feasibility and early outcomes of a curvature-guided strategy that guides dual-branch revascularization during Zone 1 Thoracic Endovascular Aortic Repair (TEVAR) based on whether the aortic pathology is predominantly located on the greater or lesser curvature of the arch. Methods: In this retrospective, descriptive study (February 2023–June 2024), 43 consecutive patients were included under a predefined anatomical protocol. Of these, 3 patients (7.0%) were lost to follow-up and were included in the analysis of baseline characteristics and perioperative outcomes. The remaining 40 patients constituted the per-protocol follow-up cohort. Pathologies predominantly on the aortic arch’s greater curvature (n = 21) were managed with a Castor single-branched stent-graft for the left subclavian artery (LSA) and a left common carotid artery (LCCA) chimney stent. Those on the lesser curvature (n = 22) received a physician-modified endograft (PMEG). The primary outcome was technical success; secondary outcomes included safety, branch patency, and reintervention. Results: The overall technical success rate was 97.7% (100% in the Castor-chimney cohort [21/21] vs. 95.5% in the PMEG cohort [21/22]). No perioperative stroke, spinal cord ischemia, or retrograde type A dissection occurred in either cohort. Two type II endoleaks were observed: one intraoperative in the Castor-chimney cohort and one during follow-up in the PMEG cohort. Among the 40 patients (20 per cohort) who completed a median follow-up of 22.5 months, freedom from aortic-related reintervention was 95% (38/40), with one reintervention occurring in each cohort. Branch patency was 100% (20/20) in the PMEG cohort, whereas it was 95% (one asymptomatic LSA occlusion) in the Castor-chimney cohort. Conclusions: The implementation of a curvature-guided protocol, which rationally matches endograft techniques to arch anatomy, suggests acceptable early safety and efficacy for complex Zone 1 TEVAR. This anatomy-driven framework offers a potential personalized approach to dual-branch revascularization and warrants prospective validation. Full article

This study investigates the coupled quasi-static response and stable-state switching behavior of mechanically prestressed rhombic bistable composite laminates under internal pneumatic pressurization and external mechanical loading. A rhombic bistable composite laminate with embedded fluidic channels is proposed, where pneumatic pressurization is employed to reconfigure the deformation state and modulate the coupling between the laminate morphology and external actuation loads. An efficient reduced-order analytical model is developed to capture the interactions among geometric configuration, prestrain distribution, internal pressure, and external mechanical loading, enabling the rapid prediction of the deformation evolution and load–deflection response under coupled loading conditions. The main innovation of this work is integrating rhombic geometric tailoring, intrinsic pneumatic actuation, and multimode external loading into a unified analytical framework. The results demonstrate that the interior angle, prestrain distribution, and loading mode can effectively regulate equilibrium morphology, snap-through energy, and actuation efficiency. Parametric analyses reveal that the rhombic geometry introduces pronounced shear–bending coupling, providing an additional geometric degree of freedom for tailoring bistable configurations and energy barriers. In particular, a smaller interior angle generally reduces the snap-through energy barrier, whereas front-side prestrain increases the energy required for stable-state switching by enhancing the initial curvature. Comparisons among different loading modes further show that transverse point loading provides the highest energy conversion efficiency, in-plane loading requires the largest input energy, and pressure-assisted actuation exhibits intermediate efficiency. These findings provide fundamental insights and practical design guidelines for programmable morphing and load-efficient stable-state switching for rhombic composite laminates operating under coupled internal–external loading environments. Full article