The tetrapod jacket-supported offshore wind turbine is subjected to marine environmental loads, resulting in monotonic and cyclic lateral-compression-tension interaction behavior of the pile-soil system. Although the excellent applicability that has been demonstrated by three-dimensional numerical simulation for aiding the revelation of the mechanism of jacket foundation-soil interaction, a significant challenge remains in accurately reflecting the nonlinear stress-strain relationship and cyclic behavior of the soil, and others. Finite element numerical models are therefore established for laterally loaded tetrapod jacket pile foundations in this study, and a bounding surface model is adopted to simulate the elastoplastic characteristics and cyclic ratchet effect of the soil. Subsequently, a parametric analysis is conducted on different net spacings and aspect ratios of the jacket base-piles to investigate the pile deformation characteristics, bearing mechanisms, evolution of pile-soil interaction, and the internal force development under monotonic and cyclic conditions, respectively. The results indicate that under monotonic loading, the pile deformation pattern transitions from a flexible pile mode to a rigid rotational deformation mode as the aspect ratio decreases. Under cyclic loading, attention should be paid to the asynchronous accumulation of axial forces within the base-piles and its impact on overall bearing performance.

Soft wet grounds such as mud, sand, or forest soils, are difficult to navigate because it is hard to predict the response of the yielding ground and energy lost in deformation. In this article, we address the control of quadruped robots' static gait in deep mud. We present and compare six controller versions with increasing complexity that use a combination of a creeping gait, a foot-substrate interaction detection, a model-based center of mass positioning, and a leg speed monitoring, along with their experimental validation in a tank filled with mud, and demonstrations in natural environments. We implement and test the controllers on a Go1 quadruped robot and also compare the performance to the commercially available dynamic gait controller of Go1. While the commercially available controller was only sporadically able to traverse in 12 cm deep mud with a 0.35 water/solid matter ratio for a short time, all proposed controllers successfully traversed the test ground while using up to 4.42 times less energy. The results of this article can be used to deploy quadruped robots on soft wet grounds, so far inaccessible to legged robots.

This paper uses a simplified assessment method based on the excavated-induced ground movement to examine the coupling effect between adjacent excavations during construction. The finite element numerical model is established to simulate and analyze the deformation of adjacent excavations at each stage of construction. Distinct construction sequences are employed to explore the dissimilarities in the deformation characteristics of the surrounding soil and envelope after excavation. The results indicate that when adjacent excavations are excavated simultaneously, their interactions affect the soil and envelopes' deformation. The maximum ground settlement occurs at a certain distance from the edge of the excavation. As the excavation depth increased, the enclosure exhibited a more pronounced deformation. The deformation of the enclosure structure can be significantly inhibited by the spatial effect at the corners of the excavation. When adjacent pits are constructed in different construction sequences, the enclosure structure on the first constructed excavation often experiences greater deformation than on the later constructed excavation.

The 2020 Mw 6.4 Petrinja, Croatia, earthquake triggered widespread liquefaction along the Kupa, Glina, and Sava rivers. The locations of liquefaction ejecta and lateral spreading were identified through a combination of field reconnaissance and interrogation of aerial photographs. Superimposing those locations on the regional geologic map revealed the liquefaction vulnerability of Holocene terrace and flood deposits, Holocene deluviumproluvium, and Pleistocene loess deposits. Liquefaction caused damage to the land and structures, with ejecta observed both near and far from residential structures. In the free field, the ejection of silty and sandy soil accompanied the extensive ground fracturing. At residential properties, ejecta led to differential settlement, cracks in foundations, walls, and floors, and contamination of water wells. Lateral spreading resulted in the formation of ground and building cracks, house sliding and tilting, pipe breakage, and pavement damage. This article documents these observations of liquefaction and draws conclusions regarding the patterns of liquefaction observed in this earthquake. These observations will be a valuable addition to liquefaction triggering databases as there are relatively few earthquakes with magnitudes less than 6.5 that triggered extensive liquefaction, and they provide additional case histories of liquefaction in Pleistocene deposits.

Sugar maple, an economically and ecologically important tree in the northern hardwood forest, has experienced regeneration failure that in the Northeast portion of the range has been variously attributed to soil acidification and resultant changes in soil chemistry, impacts of climate change, and effects of species composition. In a 5-year study spanning a latitudinal gradient in the state of New Hampshire, we examined evidence for these three hypotheses to explain sugar maple regeneration patterns. Overall, sugar maple seedling survival was highest in the two sites with lower sugar maple abundance. Alternatively, the two other sites with greater than 50% sugar maple relative dominance shared the following outcomes: higher seed production per area, greater foliar pest damage, lower seedling survival, lower sapling density, and higher canopy maple mortality, while the sites with lower dominance of maple had opposite outcomes. Based on field data and a common garden experiment, conspecific impacts on seedling survival were related to foliar pests and fungal pathogens rather than through soil feedbacks. These results lend support to other studies encouraging promotion of stand tree diversity and avoidance of monocultures.

The quest for clean, renewable energy resources has given a global rise in offshore wind turbine (OWT) construction. As OWTs are more exposed to harsh environmental conditions, the dynamic behavior of OWTs with jacket support structures under critical loading scenarios is crucial yet least understood, which becomes more convoluted with the consideration of soil-structure interaction (SSI) effects. In addition, the seismic characteristics of such systems heavily depend on the excitation characteristics like frequency content, a feature that is still ambiguous. This research aims to examine the influence of seismic frequency contents on the dynamic characteristics and damage modes of jacket-supported OWT systems including SSI effects. The numerical model is established and validated based on a previous study, which ensures the accuracy of the numerical modeling framework. Upon validation, extensive numerical analyses are performed under earthquakes with varying frequency contents. Results reveal the relationship among the ground motion frequency, SSI, and the dynamic and damage behavior of jacket-supported OWTs, offering important insights for the improved seismic design and analysis of jacket-supported OWTs.

In complex physical systems, conventional differential equations fall short in capturing non-local and memory effects. Fractional differential equations (FDEs) effectively model long-range interactions with fewer parameters. However, deriving FDEs from physical principles remains a significant challenge. This study introduces a stepwise data-driven framework to discover explicit expressions of FDEs directly from data. The proposed framework combines deep neural networks for data reconstruction and automatic differentiation with Gauss-Jacobi quadrature for fractional derivative approximation, effectively handling singularities while achieving fast, high-precision computations across large temporal/spatial scales. To optimize both linear coefficients and the nonlinear fractional orders, we employ an alternating optimization approach that combines sparse regression with global optimization techniques. We validate the framework on various datasets, including synthetic anomalous diffusion data, experimental data on the creep behavior of frozen soils, and single-particle trajectories modeled by L & eacute;vy motion. Results demonstrate the framework's robustness in identifying FDE structures across diverse noise levels and its ability to capture integer-order dynamics, offering a flexible approach for modeling memory effects in complex systems.

Helical anchors are deep foundation systems that offer high uplift capacity due to the increased interaction area between the helix and surrounding soil, thus exhibiting strong potential for resisting frost jacking in cold-region engineering. The influence of helical anchor geometry on frost heave behavior remains a critical yet insufficiently understood factor in engineering designs. Accordingly, this study conducts experimental and numerical investigations to evaluate the effects of helix number, helix diameter, helix spacing, and freeze-thaw cycles on frost jacking and thaw-induced settlement. The results indicate that the frost jacking and residual displacement after thawing gradually decrease with increasing freeze-thaw cycles and tend to stabilize after more than three cycles. Numerical simulations show that the residual displacements for full-scale anchors range from 12% to 33% of the peak frost jacking. Anchors with a greater number of helices demonstrate improved resistance to frost jacking when the uplift capabilities are comparable. When the helix spacing ranges from 2D to 6D (where D denotes the helix diameter), the double-helix anchor with 2D spacing exhibits the highest stability during freeze-thaw cycles, followed by the anchor with 3D spacing. However, the anchor with 2D spacing yields the lowest uplift capacity under unfrozen soil conditions. Anchors with a helix spacing of 2D to 3D are recommended for resisting freeze-thaw effects, provided that this configuration does not significantly reduce the uplift capacity.

Offshore wind turbines (OWTs) empoly various foundation types, among which Jacket-type offshore wind turbines (JOWTs) are often used in shallow waters with challenging soil conditions due to their lattice framework foundations and multiple anchoring points. However, prolonged exposure to harsh marine environments (e.g. storms) and age-related degradation issues like corrosion, fatigue cracking, and mechanical damage increases failure risks. To address these issues, this paper introduces a Digital Healthcare Engineering (DHE) framework, which provides a proactive strategy for enhancing the safety and sustainability of JOWTs: (1) Real-time health monitoring using IoT; (2) Data transmission via advanced communication technologies; (3) Analytics and simulations using digital twins; (4) AI-powered diagnostics and recommendations; as well as (5) Predictive analysis for maintenance planning. The paper reviews recent technological advances that support each DHE module, assesses the framework's feasibility. Additionally, a prototype DHE system is proposed to enable continuous, early fault detection, and health assessment.

In recent years, copper pollution has gradually become one of the major problems of soil environmental pollution. Lignin plays an important role in plant resistance to biotic and abiotic stresses. CCoAOMT is a key enzyme in the lignin biosynthesis process. In this study, the CCoAOMT gene family members of Platycodon grandiflorus were identified by bioinformatics methods, and their basic characteristics and potential functions were analyzed. The results showed that five members of the PgCCoAOMT gene family were identified in P. grandiflorus, with protein lengths ranging from 246 to 635 amino acids, and were evenly distributed on four chromosomes. Phylogenetic analysis indicated that the PgCCoAOMT gene family was divided into two subclades, namely Clade1a, Clade1b, Clade1c, Clade1d, and Clade2. The cis-regulatory element analysis of the promoter revealed that the PgCCoAOMT members contained a large number of cis-regulatory elements responsive to stress, and conjecture PgCCoAOMT2, PgCCoAOMT4, and PgCCoAOMT5 were involved in the lignin synthesis. The qRT-PCR results showed that, within 5 days of copper stress treatment, except for the PgCCoAOMT4 gene, the other genes exhibited different expression levels. Furthermore, the expression levels of all five PgCCoAOMT genes increased significantly at 7 days of treatment. With the increase in the number of days of treatment, the content of lignin in the seedings of P. grandiflorus showed a trend of increasing first and then decreasing under copper stress. In general, in the copper stress treatment of 1-3 days, the transcriptional inhibition of PgCCoAOMT1 and PgCCoAOMT3 and the increase in lignin content contradicted each other, suggesting that there was post-translational activation or alternative metabolic pathways compensation. Meanwhile, in the 7-day treatment, the coordinated up-regulation of the genes was accompanied by the failure of lignin synthesis, which pointed to the core bottleneck of metabolic precursors depletion and enzyme activity inactivation caused by root damage. Research objective: This study reveals the expression level of the PgCCoAOMT gene in the seedings of P. grandiflorus under copper stress, providing a theoretical basis for elucidating the mechanism of P. grandiflorus response to copper stress and for subsequent improvement of root resistance in P. grandiflorus.