Search Results (1,210)

Bolted connections are critical in deep-sea engineering, yet classical theories (such as VDI 2230) implicitly assume atmospheric pressure conditions, neglecting the volume contraction of components due to hydrostatic pressure. This fundamental flaw hinders accurate prediction of preload retention—especially when bolts and clamped components exhibit differential compressibility (a common scenario in practical applications). To bridge this scientific gap, this paper establishes the first analytical model for bolt preload under pressure-induced volumetric contraction based on deformation coordination relations. The derived closed-form expressions explicitly quantify residual preload as a function of deep-sea ambient pressure, component bulk modulus, and geometric parameters. Model predictions closely match finite element calculations, showing that stainless steel bolts clamping aluminum alloys under 110 MPa pressure can experience up to a 40% preload reduction. This theoretical framework extends classical bolt connection mechanics to high-pressure environments, providing a scientific basis for optimizing deep-sea connection designs through material matching and dimensional control to effectively mitigate pressure-induced preload loss. Full article

Facial Expression Recognition (FER) is a critical component of affective computing, with deep learning models dominating performance metrics. In contrast, geometric approaches based on the Facial Action Coding System (FACS) offer explainability through using triangles aligned to facial landmarks. The notable points of these triangles capture the deformation of muscles. However, restricting the feature extraction to notable points may be suboptimal. This paper introduces a novel method for optimizing the extraction of features by searching for optimal inner points in 22 facial triangles applying three metaheuristics: Differential Evolution (DE), Particle Swarm Optimization (PSO), and Convex Partition (CP). This results in a set of 59 geometric-based descriptors that capture muscle deformation more accurately. The proposed method was evaluated using five machine learning classifiers on two benchmark databases: the Karolinska Directed Emotional Faces (KDEF) and the Japanese Female Facial Expression (JAFFE). Experimental results demonstrate significant performance improvements. The combination of DE with a Multi-Layer Perceptron (MLP) achieved an accuracy of $0.91$ on the KDEF database, while Support Vector Machine (SVM) optimized via CP attained an accuracy of $0.81$ on the JAFFE database. Statistical analysis confirms that optimized descriptors yield higher accuracy than previous geometric methods. Full article

Ground fissures are widespread around the world and are particularly severe in the North China Plain. In order to investigate the crack propagation path and propagation mode of buried ground fissures from deep strata to the surface, physical simulation experiments and numerical simulation experiments were conducted based on the sand–clay interlayer strata in the Longyao area. The results show that during the settlement of the hanging wall strata, the propagation path of the cracks changes due to differences in soil properties. The crack propagation is interrupted in the sand layer and slowed down in the clay layer. The surface displacement is characterized by an alternating sequence of gradual and rapid growth phases. The process of crack propagation from depth to surface is divided into five stages, forming tensile cracks and causing the differential settlement of the surface. The strata are mainly under tensile stress, with the stress range of the hanging wall being 2.1 to 3.0 times that of the footwall. Under identical experimental conditions, buried ground fissures in the strata of sand–clay interlayers exhibit anti-dip crack propagation angles and surface deformation zone widths that are between those of homogeneous silty clay and sand. Based on the experimental results, an analytical formula for the hanging wall deformation zone was further proposed. The research results can provide an important reference and theoretical basis for the investigation and disaster prevention of buried ground fissures in the Longyao area of Hebei Province. Full article

Excavation of ultra-shallow pilot tunnels triggers surface settlement and endangers surrounding pipelines. The discontinuous settlement curve from traditional stochastic medium theory cannot be directly integrated into the foundation beam model, limiting pipeline deformation prediction accuracy. The key novelty of this study lies in proposing an improved coupled method tailored to ultra-shallow burial conditions: converting the discontinuous settlement solution into a continuous analytical one via polynomial fitting, embedding it into the Winkler elastic foundation beam model, and realizing pipeline settlement prediction by solving the deflection curve differential equation with the initial parameter method and boundary conditions. Four core factors affecting pipeline deformation are identified, with pilot tunnel size as the key. Shallower depth (especially 5.5 m) intensifies stratum disturbance; pipeline parameters (diameter, wall thickness, elastic modulus) significantly impact bending moment, while stratum elastic modulus has little effect on settlement. Verified by the Xueyuannanlu Station project of Beijing Rail Transit Line 13, theoretical and measured settlement trends are highly consistent, with core indicators meeting safety requirements (max theoretical/measured settlement: −10.9 mm/−8.6 mm < 30 mm; max rotation angle: −0.066° < 0.340°). Errors (max 5.1 mm) concentrate at the pipeline edge, and conservative theoretical values satisfy engineering safety evaluation demands. Full article

LuTan-1(LT-1) is the first Chinese civil L-band satellite constellation for geohazard observation, comprising LT-1A and LT-1B satellites. By employing interferometric altimetry and differential deformation measurement technologies, it achieves high-precision topographic mapping and establishes sub-millimeter-level deformation monitoring capabilities. To meet the high-precision measurement requirements for applications such as topographic surveying and deformation monitoring, this study systematically evaluates four categories of image quality metrics—geometric, radiometric, and polarimetric characteristics, as well as orbital and baseline quality—based on in-orbit test data from the twin satellites. The test results demonstrate that all image quality indicators of the LT-1 SAR satellites meet the design specifications, confirming that the imagery can provide robust spatial technical support for applications including geological hazard monitoring, land resource investigation, earthquake assessment, disaster prevention and mitigation, fundamental surveying and mapping, and forestry monitoring. Full article

Background: Ventricular function assessments in Fontan patients remain challenging. Ejection fraction (EF) lacks sensitivity for early dysfunction, and the roles of strain and advanced imaging in systemic left ventricle (LV) physiology are not fully defined. We aimed to compare (i) LV and atrial strain indices between pediatric Fontan patients with preserved EF (P-LVEF) versus reduced EF (R-LVEF) and (ii) echocardiographic global longitudinal strain, segmental longitudinal strain indices, and conventional 2D and 3D echocardiographic parameters through cardiac morphology. Methods: Pediatric patients with Fontan circulation and systemic LV morphology underwent clinical, hemodynamic, and multimodality echocardiographic evaluation, including 2D/3D parameters, global and segmental LV strain, and left atrial strain. Outcomes were analyzed according to EF status and congenital morphology. Significant results from multiple comparisons were followed by post hoc analysis, where appropriate. Results: Patients with a reduced EF exhibited a worse clinical status, a higher pulmonary vascular resistance index, and greater systemic congestion compared with those with a preserved EF. Conventional 2D indices showed no significant differences between the two studied groups except for LV end-systolic volume (ESV) (p = 0.0315) and LV end-systolic longitudinal diameter (ESL) (p = 0.0024), which showed higher values in the R-LVEF group. Although the relative frequency of impaired deformation was higher in Fontan patients with an unbalanced atrioventricular canal compared with the Fontan patients with a tricuspid atresia + pulmonary stenosis + ventricular septal defect, the difference did not reach statistical significance (p = 0.1365). Most segmental longitudinal strain values were not significantly different across patients with different cardiac morphology, except for the basal anterior segment and apical inferoseptal segment (p < 0.05). Conclusions: In pediatric Fontan patients with systemic LV morphology, a reduced EF was associated with a worse clinical and hemodynamic status. Conventional echocardiographic indices showed a limited ability to differentiate between the compared groups. Although no statistically significant differences were detected between pediatric Fontan patients with preserved EF and reduced EF, LV and atrial strain indices provided complementary information on ventricular–atrial interactions and myocardial deformation. These findings are exploratory and warrant confirmation in larger, prospective studies. Full article

Within the field of the structural monitoring of bridges, numerous technologies and methodologies have been developed. Among these, methods based on synthetic aperture radar (SAR) which utilise satellite data from missions such as Sentinel-1 (European Space Agency-ESA) and COSMO-SkyMed (Agenzia Spaziale Italiana—ASI) to capture displacements, temperature-related changes, and other geophysical measurements have gained increasing attention. However, SAR has yet to establish its value and potential fully; its broader adoption hinges on consistently demonstrating its robustness through recurrent applications, well-defined use cases, and effective strategies to address its inherent limitations. This study presents a systematic literature review (SLR) conducted in accordance with key stages of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 framework. An initial corpus of 1218 peer-reviewed articles was screened, and a final set of 25 studies was selected for in-depth analysis based on citation impact, keyword recurrence, and thematic relevance from the last five years. The review critically examines SAR-based techniques—including Differential Interferometric SAR (DInSAR), multi-temporal InSAR (MT-InSAR), and Persistent Scatterer Interferometry (PSI), as well as approaches to integrating SAR data with ground-based measurements and complementary digital models. Emphasis is placed on real-world case studies and persistent technical challenges, such as atmospheric artefacts, Line-of-Sight (LOS) geometry constraints, phase noise, ambiguities in displacement interpretation, and the translation of radar-derived deformations into actionable structural insights. The findings underscore SAR’s significant contribution to the structural health monitoring (SHM) of bridges, consistently delivering millimetre-level displacement accuracy and enabling engineering-relevant interpretations. While standalone SAR-based techniques offer wide-area monitoring capabilities, their full potential is realised only when integrated with complementary procedures such as thermal modelling, multi-sensor validation, and structural knowledge. Finally, this document highlights the persistent technical constraints of InSAR in bridge monitoring—including measurement ambiguities, SAR image acquisition limitations, and a lack of standardised, automated workflows—that continue to impede operational adoption but also point toward opportunities for methodological improvement. Full article

This paper presents ACTD-Net (Attention-Convolutional Transformer Denoising Network), a novel hybrid deep learning approach for speckle noise reduction from differential synthetic aperture radar (SAR) interferometric phase maps. Differential interferometric SAR (DInSAR) is a powerful technique for detecting and quantifying surface deformations, but the obtained phase maps are corrupted by speckle noise, topographic contributions, and atmospheric artifacts. Effective speckle denoising is crucial for accurate extraction of the desired deformation information. ACTD-Net combines the strengths of convolutional neural networks (CNNs) and vision transformers (ViTs) in a two-stage architecture. First, a modified U-Net model with residual connections performs initial despeckling of the input DInSAR phase map. Then, the denoised phase map is fed into a Swin Transformer adapted with a masked self-attention mechanism, which further refines the denoising while preserving fine details and discontinuities related to surface deformations. Experimental results on simulated and real DInSAR data, including from the September 2023 Morocco earthquake region, demonstrate the effectiveness of ACTD-Net, outperforming traditional techniques and current deep learning methods in terms of quantitative metrics such as peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and edge preservation index (EPI). The comprehensive evaluation shows that ACTD-Net achieves up to 33.55 dB PSNR, 0.96 SSIM, and 0.94 EPI on simulated data, and 33.62 ± 2.75 dB PSNR on 388 real Morocco earthquake patches, with significant improvements in preserving phase discontinuities and reducing unwrapping errors by approximately 62% on real earthquake data. Full article

Long-term settlement of dredger fill presents substantial challenges to infrastructure stability, particularly in coastal areas such as Tianjin Nangang, where liquefied natural gas (LNG) pipelines are vulnerable to deformation caused by differential settlements. This study investigates the geological properties and long-term settlement characteristics of dredger fill in the Tianjin Nangang coastal zone and develops a simplified predictive model for long-term settlement. Comprehensive laboratory analyses, including field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP), revealed a porous, flaky microstructure dominated by quartz and calcite, with mesopores (0.03–0.8 µm) constituting over 80% of total pore volume. A centrifuge modelling test conducted at 70 g acceleration simulated accelerated settlement behavior, demonstrating that approximately 70% of settlements occured within the initial year. The study proposes an enhanced hyperbolic model for long-term settlement prediction, which shows excellent correlation with experimental results. The findings underscore the high compressibility and low shear strength of dredger fill, highlighting the necessity for specific mitigation measures to ensure infrastructure integrity. This research establishes a simplified yet reliable methodology for settlement estimation, providing valuable practical guidance for coastal land reclamation projects. Full article

Differential speed rolling (DSR) has been recognized as a unique processing technique in recent years, which has been used to plastically deform Mg-based alloys and to investigate the role of dynamic recrystallization (DRX) and its influence on both microstructure and mechanical properties. In this study, Mg–2Al–0.5Ca–0.5Mn (AXM20504) was solution-heat-treated (T4 condition) and subjected to single-pass DSR at both 20 and 40% thickness reductions, followed by post-annealing at temperatures of 350, 400, and 450 °C for the durations of 20, 40, and 60 min to evaluate the onset and development of static recrystallization (SRX) and its overall effect on the formability of Mg-based alloys. The results demonstrate how post-annealing yields nearly complete SRX at 400 °C for 60 min and 450 °C for 40 min with a significant improvement in ductility, increasing from 5% to 12% while maintaining an average tensile strength above 200 MPa. Thus, the improvement in mechanical properties demonstrates that post-annealing can deliver significant potential in terms of the enhanced formability of Mg alloys used in sheet metal forming applications. Full article

High-precision and high-resolution surface deformation provide crucial constraints for studying the kinematic characteristics and dynamic mechanisms of crustal movement. Considering the limitations of existing geodetic observations, we used Sentinel-1 SAR images and accurate GNSS velocity to obtain a high-resolution three-dimensional (3D) surface velocity map across the Laohushan segment and the 1920 Haiyuan earthquake rupture zone of the Haiyuan Fault on the northeastern Tibetan Plateau. We tied the InSAR LOS (Line of Sight) velocity to the stable Eurasian reference frame adopted by GNSS. Using Kriging interpolation constrained by GNSS north–south components, we decomposed the ascending and descending InSAR velocities into east–west and vertical components to derive a high-resolution 3D deformation. We found that a sharp velocity gradient extending ~45 km along the strike of the Laohushan segment, with a differential movement of ~3 mm/a across the fault, manifests in the east–west velocity component, suggesting that shallow creep has propagated to the surface. However, the east–west velocity component did not exhibit an abrupt discontinuity in the rupture zone of the Haiyuan earthquake. Subsidence caused by anthropogenic and hydrological processes in the region, such as groundwater extraction, coal mining, and hydrologic effects, exhibited distinct distribution characteristics in the vertical velocity component. Our study provides valuable insights into the crustal movement in this region. Full article

Background/Objectives: The poultry industry faces severe heat-stress challenges that threaten both economic sustainability and animal welfare. Embryonic thermal manipulation (ETM) has been proposed as a thermal programming strategy to enhance chick heat tolerance, yet its efficacy in layers requires verification, and its effects on growth performance and neurodevelopment remain unclear. Methods: White Leghorn embryos at embryonic days 13 to 18 (ED 13–18) were exposed to 39.5 °C (ETM). Hatch traits and thermotolerance were recorded, and morphometric and histopathological analyses were performed on brain sections. Transcriptome profiling of the whole brains and hypothalami was conducted to identify differentially expressed genes (DEGs). Representative pathway genes responsive to ETM were validated by RT-qPCR. Results: ETM reduced hatchability, increased deformity rate, and decreased hatch weight and daily weight gain. During a 37.5 °C challenge, ETM chicks exhibited delayed panting and lower cloacal temperature. Histopathology revealed impaired neuronal development and myelination. Transcriptomic analysis of ED18 whole brains showed DEGs enriched in neurodevelopment, stimulus response, and homeostasis pathways. RT-qPCR confirmed hypothalamic sensitivity to ETM: up-regulation of heat-shock gene HSP70, antioxidant gene GPX1, the inflammatory marker IL-6, and apoptotic genes CASP3, CASP6, CASP9; elevated neurodevelopmental marker DCX, indicative of a stress-responsive neuronal state; and reduced orexigenic neuropeptide AGRP. Conclusions: ETM improves heat tolerance in layers but compromises hatching performance and brain development, with widespread perturbation of hypothalamic stress responses and neurodevelopmental gene networks. These findings elucidate the mechanisms underlying ETM and provide a reference for enhancing thermotolerance in poultry. Full article

Maintaining the stability of the mine roadway is of paramount importance, as it is critical in ensuring the daily operational continuity, personnel safety, long-term economic viability, and sustainability of the entire mining operation. Significant instability can trigger serious disruptions—such as production stoppages, equipment damage, and severe safety incidents—which ultimately compromise the project’s financial returns and future prospects. Therefore, the proactive assessment and rigorous control of roadway stability constitute a foundational element of successful and sustainable resource extraction. In China, thick and extra-thick coal seams constitute over 44% of the total recoverable coal reserves. Consequently, their safe and efficient extraction is considered vital in guaranteeing energy security and enhancing the efficiency of resource utilization. The surrounding rock of gob-side roadways in typical coal seams is often fractured due to high ground stress, intensive mining disturbances, and overhanging goaf roofs. Consequently, asymmetric failure patterns such as bolt failure, steel belt tearing, anchor cable fracture, and shoulder corner convergence are common in these entries, which pose a serious threat to mine safety and sustainable mining operations. This deformation and failure process is associated with several parameters, including the coal seam thickness, mining technology, and surrounding rock properties, and can lead to engineering hazards such as roof subsidence, rib spalling, and floor heave. This study proposes countermeasures against asymmetric deformation affecting gob-side entries under intensive mining pressure during the fully mechanized caving of extra-thick coal seams. This research selects the 8110 working face of a representative coal mine as the case study. Through integrated field investigation and engineering analysis, the principal factors governing entry stability are identified, and effective control strategies are subsequently proposed. An elastic foundation beam model is developed, and the corresponding deflection differential equation is formulated. The deflection and stress distributions of the immediate roof beam are thereby determined. A systematic analysis of the asymmetric deformation mechanism and its principal influencing factors is conducted using the control variable method. A support approach employing a mechanical constant-resistance single prop (MCRSP) has been developed and validated through practical application. The findings demonstrate that the frequently observed asymmetric deformation in gob-side entries is primarily induced by the combined effect of the working face’s front abutment pressure and the lateral pressure originating from the neighboring goaf area. It is found that parameters including the immediate roof thickness, roadway span, and its peak stress have a significant influence on entry convergence. Under both primary and secondary mining conditions, the maximum subsidence shows an inverse relationship with the immediate roof thickness, while exhibiting a positive correlation with both the roadway span and the peak stress. Based on the theoretical analysis, an advanced support scheme, which centers on the application of an MCRSP, is designed. Field monitoring data confirm that the peak roof subsidence and two-side closure are successfully limited to 663 mm and 428 mm, respectively. This support method leads to a notable reduction in roof separation and surrounding rock deformation, thereby establishing a theoretical and technical foundation for the green and safe mining of deep extra-thick coal seams. Full article

In this research, we establish a precise correspondence between the theory of logarithmic connections on principal G-bundles over compact Riemann surfaces and the geometric formulation of control systems on curved manifolds, providing a novel differential–geometric framework for analyzing optimal control problems with non-holonomic constraints. By characterizing control systems through the geometric structure of flat connections with logarithmic singularities at marked points, we demonstrate that optimal trajectories correspond precisely to horizontal lifts with respect to the connection. These horizontal lifts project onto geodesics on the punctured surface, which is equipped with a Riemannian metric uniquely determined by the monodromy representation around the singularities. The main geometric result proves that the isomonodromic deformation condition translates into a compatibility condition for the control system. This condition preserves the conjugacy classes of monodromy transformations under variations of the marked points, and ensures the existence and uniqueness of optimal trajectories satisfying prescribed boundary conditions. Furthermore, we analyze systems with non-holonomic constraints by relating the constraint distribution to the kernel of the connection form, showing how the degree of non-holonomy can be measured through the failure of integrability of the associated horizontal distribution on the principal bundle. As an application, we provide computational implementations for $\mathrm{SL}(2,\mathbb{C})$ connections over hyperbolic Riemann surfaces with genus $g\ge 2$, explicitly constructing the monodromy-induced metric via the Poincaré uniformization theorem and deriving closed-form expressions for optimal control strategies that exhibit robust performance characteristics under perturbations of initial conditions and system parameters. Full article

To investigate the performance of horizontally reinforced composite foundations in resisting surface rupture of normal faults, this study designed and conducted a series of physical model tests. A systematic comparative analysis was performed on the fracture resistance of sites with three-layer sand, five-layer sand, and three-layer clay geogrid horizontally reinforced composite foundations under 70° normal fault dislocation. The results indicate that significant changes in earth pressure serve as a precursor indicator of fault rupture, and their evolution process reveals the internal energy accumulation and release mechanism. Increasing the number of geogrid layers significantly enhances the lateral confinement of the foundation, resulting in a narrower macro-rupture zone located farther from the structure in sand sites, and promotes the formation of a step-fault scarp deformation mode at the surface, which is more conducive to structural safety. Under identical reinforcement conditions, the clay site exhibited comprehensively superior fracture resistance compared to the sand site due to the soil cohesion and stronger interfacial interaction with the geogrids, manifested as more significant deviation of the rupture path, and lower microseismic accelerations and structural strains transmitted to the building. Comprehensive analysis confirms that employing geogrid-reinforced composite foundations can effectively guide the surface rupture path and improve the deformation pattern, representing an effective engineering measure for mitigating disaster risk for buildings spanning active faults. Full article