Search Results (1,248)

Urban mobility in Bangkok is constrained by congestion, modal fragmentation, and gaps in First and Last Mile (FLM) access. This study develops a GIS-based framework that combines maximal-coverage location allocation with post-optimization accessibility diagnostics to inform intermodal hub siting. The network model compares one-, three-, and five-hub configurations using a 20 min coverage standard, and we conduct sensitivity tests at 15 and 25 min to assess robustness. Cumulative isochrones and qualitative overlays on BTS, MRT, SRT, Airport Rail Link, and principal water routes are used to interpret spatial balance, peripheral reach, and multimodal alignment. In the one-hub scenario, the model selects Pathum Wan as the optimal central node. Transitioning to a small multi-hub network improves geographic balance and reduces reliance on the urban core. The three-hub arrangement strengthens north–south accessibility but leaves the west bank comparatively underserved. The five-hub configuration is the most spatially balanced and network-consistent option, bridging the west bank and reinforcing rail interchange corridors while aligning proposed hubs with existing high-capacity lines and waterway anchors. Methodologically, the contribution is a transparent workflow that pairs coverage-based optimization with isochrone interpretation; substantively, the findings support decentralized, polycentric hub development as a practical pathway to enhance FLM connectivity within Bangkok’s current network structure. Key limitations include reliance on resident population weights that exclude floating or temporary populations, use of typical network conditions for travel times, a finite pre-screened candidate set, and the absence of explicit route choice and land-use intensity in the present phase. Full article

Digital Twin (DT) technology has rapidly matured from pilot projects to integral components of advanced asset management and process optimization in the oil and gas (O&G) industry. This review provides a structured synthesis of the current state of digital twin frameworks, with a focus on offshore and topside gas-processing systems, such as those found on Floating Production Storage and Offloading (FPSO). Emphasis is placed on high-fidelity process simulations and scalable architectures integrating real-time data with advanced analytics. Drawing on over 85 peer-reviewed sources and industrial frameworks, the paper outlines modular DT architectures, encompassing steady-state and dynamic process simulations (e.g., Aspen HYSYS), reduced-order and hybrid machine learning models, co-simulation environments, and advanced equation-of-state packages (e.g., GERG-2008). Special attention is given to compressor map integration, Equations of State (EOS) selection, ISO/IEC standard compliance, and digital thread continuity. Additionally, the review explores economic and sustainability-driven DT implementations, including flare and methane mitigation, ISO 50001-aligned energy optimization, and lifecycle/decommissioning strategies. It concludes with a technical and economic assessment of DT maturity for gas compression facilities, identifying research gaps in standardization, long-term validation, and cybersecurity integration. The insights provided are intended to support decision-makers, engineers, and researchers in deploying scalable, auditable, and high-impact DT solutions across the O&G value chain. Full article

Cyanobacteria harmful algal blooms (CHABs) are most commonly caused by the proliferation of the toxic species, Microcystis aeruginosa. It is therefore of considerable interest to develop biological control processes which are economically feasible and scalable for this cyanobacteria that produces the cyanotoxin, microcystin. Some gastropods that are abundant in freshwater ecosystems can filter feed on floating planktonic microphytes. We investigated this in the freshwater snail, Sinotaia aeruginosa which indiscriminately accumulated M. aeruginosa, Chlorella vulgaris, and Trichormus variabilis (syn. Anabaena variabilis) The initial filtration rates were approx. 44 and 19 mL · g_wwt⁻¹ · h⁻¹ for unicellular and colony-forming M. aeruginosa, respectively. The pseudofaeces that were formed directly by filtration possessed a limited period of stability, and the bulk of the M. aeruginosa from pseudofaeces was eventually released back to the water column as undigested cyanobacteria. Nevertheless, the rate of sequestration of colonial M. aeruginosa into pseudofaeces was greater than its rate of release, thereby indicating that the temporary stability of pseudofaeces alone would be adequate to impede bloom formation. Therefore, these results provide evidence for using this gastropod in an effective preventative strategy for CHABs formation. Our results highlight the importance of understanding the impact of feeding mechanisms on ecosystem structure when proposing their use in biomanipulative processes aimed at correcting cyanobacteria impacted ecosystems. Full article

With the transformation of the global energy structure, offshore wind power is developing on a large scale, and the efficient and safe installation of offshore converter platforms has become a key technological bottleneck. Based on the elastic force–gravity similarity principle, a 1:65 model scale was adopted. A physical model of the offshore converter station platform was constructed, and the accuracy of the numerical simulation was validated by comparison with the physical model tests. This study investigates the dynamic response of the offshore converter platform and converter valve equipment during the float-over installation and mating process. The structural dynamic responses at key positions were analyzed. The results indicate that, due to the slender and flexible structure of the converter valve equipment, the Z-direction acceleration at the top is about 20% higher than that at the bottom. Moreover, the stress and strain at the bottom connection with the deck are higher than those at the top. The Y-direction acceleration at the edge foundation beam of the platform module is 47% higher than that at the mid-span position. The vibration frequency of the foundation beam on the first floor with the converter valve arranged is increased by 15%. When the jacket piles are subjected to impact, the mid-span response is 25% higher than that at the edges, showing characteristics of “strong at mid-span and weak at the edges”. Full article

The external floating roof of a large storage tank directly covers the liquid surface as the liquid level rises and falls, enhancing the tank’s safety and environmental performance. It is fabricated from thin SA516 Gr.70 steel plates, with a carbon equivalent of 0.37% calculated according to AWS standards, using single-sided butt welding. Such plates are susceptible to welding-induced deformations, resulting in irregular warping of the bottom plate. Current research on floating roofs for storage tanks mostly relies on idealized models that assume no deformation, thereby neglecting the actual deformation characteristics of the floating roof structure. To address this, the present study develops an automated modeling approach that reconstructs a three-dimensional floating roof model based on measured deformation data, accurately capturing the initial irregular geometry of the bottom plate. This method employs parametric numerical reconstruction and automatic finite element model generation techniques, enabling efficient creation of the irregular initial deformation caused by welding of the floating roof bottom plate and its automatic integration into the finite element analysis process. It overcomes the inefficiencies, inconsistent accuracy, and challenges associated with traditional manual modeling when conducting large-scale strength analyses under in-service conditions. Based on this research, a strength analysis of the deformed floating roof structure was conducted under in-service conditions, including normal floating, extreme rainfall, and outrigger contact scenarios. An idealized geometric model was also established for comparative analysis. The results indicate that under the normal floating condition, the initial irregular deformation increases the local stress peak of the floating roof bottom plate by 19%, while the maximum positive and negative displacements increase by 22% and 83%, respectively. Under extreme uniform rainfall conditions, it raises the stress peak of the bottom plate by 24%, with maximum positive and negative displacements increasing by 21% and 28%, respectively. Under the extreme non-uniform rainfall condition, it significantly elevates the stress peak of the bottom plate by 227%, and the maximum positive and negative displacements increase by 45% and 47%, respectively. Under the outrigger bottoming condition, it increases the local stress peak of the bottom plate by 25%, with maximum positive and negative displacements remaining similar. The initial irregular deformation not only significantly amplifies the stress and displacement responses of the floating roof bottom plate but also intensifies the deformation response of the top plate through structural stiffness weakening and deformation coupling, thereby reducing the safety margin of the floating roof structure. This study fills the knowledge gap regarding the effect of welding-induced irregular deformation on floating roof performance and provides a validated workflow for automated modeling and mechanical assessment of large-scale welded steel structures. Full article

The vibrations induced by urban rail transit are exerting an increasingly prominent influence on the surrounding buildings and human health. As a prevalent track defect, rail corrugation can exacerbate the vibrations generated during train operation. In this study, on-site measurements were carried out to investigate the characteristics of rail corrugation in the small-radius curve segments of subways. The differences in rail corrugation with and without vibration mitigation measures were analyzed. Additionally, the vibration responses of adjacent buildings in the steel spring floating slab track segments with rail corrugation were examined. The findings of this study indicate that in the small-radius curve segments of the steel spring floating slab track, there exists a rail corrugation phenomenon with a wavelength of 200 mm. This leads to inadequate vibration attenuation in the 80 Hz frequency band, allowing some vibration energy to still be transmitted to adjacent buildings. Nevertheless, the vibration responses of buildings are predominantly governed by their own structural vibration modes. Full article

Image classification is central to computer vision, supporting applications from autonomous driving to medical imaging, yet state-of-the-art convolutional neural networks remain constrained by heavy floating-point operations (FLOPs) and parameter counts on edge devices. To address this accuracy–efficiency trade-off, we propose a unified lightweight framework built on a pruning-aware coordinate attention block (PACB). PACB integrates coordinate attention (CA) with L1-regularized channel pruning, enriching feature representation while enabling structured compression. Applied to MobileNetV3 and RepVGG, the framework achieves substantial efficiency gains. On GTSRB, MobileNetV3 parameters drop from 16.239 M to 9.871 M (–6.37 M) and FLOPs from 11.297 M to 8.552 M (–24.3%), with accuracy improving from 97.09% to 97.37%. For RepVGG, parameters fall from 7.683 M to 7.093 M (–0.59 M) and FLOPs from 31.264 M to 27.918 M (–3.35 M), with only ~0.51% average accuracy loss across CIFAR-10, Fashion-MNIST, and GTSRB. Complexity analysis further confirms PACB does not increase asymptotic order, since the additional CA operations contribute only lightweight lower-order terms. These results demonstrate that coupling CA with structured pruning yields a scalable accuracy–efficiency trade-off under hardware-agnostic metrics, making PACB a promising, deployment-ready solution for mobile and edge applications. Full article

Floating breakwater layouts require flexible adjustment to accommodate sheltered area bathymetry. However, most studies have focused solely on straight layouts and have neglected the influence of complex nearshore bathymetry and structures. This work investigates streamlined-layout double-row floating breakwaters with wing plates designed for a specific port. Wave attenuation performance, motion responses, mooring tensions, and surface wave pressures under realistic nearshore conditions are systematically evaluated through a water tank experiment. The results demonstrate that the wave attenuation performance improves as incident wave height and period decrease, with the attenuation rate increasing by 6.32~11.05%. However, both the motion responses and the uplift pressures on the head and tail modules change slightly. The maximum prototype-scale changes in the maximum amplitudes of surge, heave, and pitch are +0.0625 m, −0.488 m, and +3.8523°, respectively, and the uplift pressures on the head and tail modules exhibit maximum changes of +2.3 kPa and −5.6 kPa, respectively. Additionally, wave reflection induced by nearshore structures influences both harbor tranquility and breakwater motion response. Full article

Urban park green spaces (UPGSs) play a critical role in enhancing residents’ quality of life, particularly for older adults. However, inequities in accessibility and resource distribution remain persistent challenges in aging urban areas. To address this issue, this study takes Gulou District, Nanjing City, as an example and proposes a comprehensive framework to evaluate the overall quality of UPGSs. Furthermore, an enhanced Gaussian two-step floating catchment area (2SFCA) method is introduced that incorporates (1) a multidimensional park quality score derived from an objective evaluation system encompassing ecological conditions, service quality, age-friendly facilities, and basic infrastructure; and (2) a Gaussian distance decay function calibrated to reflect the walking and public transit mobility patterns of the older adults in the study area. The improved method calculates the accessibility values of UPGSs for older adults living in residential communities under the walking and public transportation scenarios. Finally, factors influencing the social equity of UPGSs are analyzed using Pearson correlation coefficients. The experimental results demonstrate that (1) high-accessibility service areas exhibit clustered distributions, with significant differences in accessibility levels across the transportation modes and clear spatial gradient disparities. Specifically, traditional residential neighborhoods often present accessibility blind spots under the walking scenario, accounting for 50.8%, which leads to insufficient accessibility to public green spaces. (2) Structural imbalance and inequities in public service provision have resulted in barriers to UPGS utilization for older adults in certain communities. On this basis, targeted improvement strategies based on accessibility characteristics under different transportation modes are proposed, including the establishment of multi-tiered networked UPGSs and the upgrading of slow-moving transportation infrastructure. The research findings can enhance service efficiency through evidence-based spatial resource reallocation, offering actionable insights for optimizing the spatial layout of UPGSs and advancing the equitable distribution of public services in urban core areas. Full article

The current paper presents a comparative analysis between a high-fidelity simulation tool and computational fluid dynamics (CFD) in evaluating the behavior of a fully coupled floating offshore wind turbine (FOWT) system subjected to three distinct design load cases, with a particular emphasis on extreme weather scenarios. While both approaches yielded comparable results under standard operational conditions, noticeable discrepancies emerged in surge drift and mooring line tension during typhoon conditions. The present work highlighted a significant limitation of standard calibration methods based on free-deck motion that are not reflective of the unique features of extreme environmental responses. To address this limitation, a novel calibration methodology is suggested that uses drag coefficients derived from direct measurement of extreme load cases. The prediction accuracy of the high-fidelity simulation model was significantly improved by refining the transverse component of the drag coefficients of major structural components, decreasing prediction accuracy of surge and mooring tension responses from almost 30% error to about 5%. Further, despite increasing the fidelity of calibration under extreme environmental conditions, it is primarily contingent on high-fidelity measurements corresponding to the use of the most conventional calibration approach under normal environmental conditions. Ultimately, the results demonstrate the need for accurate calibration approaches to provide reliable performance predictions of FOWT systems under varying extreme environmental conditions. Full article

Offshore wind turbines (OWTs) are being developed with larger capacities for deeper waters, facing complex environmental loads that challenge structural safety. In contrast to onshore turbines, OWT foundations must withstand combined hydrodynamic forces (waves and currents), leading to substantially higher construction costs. For floating offshore wind turbines (FOWTs), additional considerations include radiation hydrodynamic loads and additional hydrodynamic damping effects caused by platform motion. Dynamic analysis of these foundations remains a critical bottleneck, presenting new challenges for offshore wind power advancement. This article first introduces the main structural types of OWT foundations, with case studies predominantly from China. The remaining part of the article proceeds as follows: dynamics of fixed OWT foundations, dynamics of FOWT foundations, and conclusions. Next, it covers several important topics related to fixed offshore wind turbines, including pile–soil interaction, wave loads, and seismic analysis. It then discusses support platform motion analysis, hydroelastic analysis, and mooring system characteristics of floating offshore wind turbines. Finally, it presents some insights to improve design and optimization methods for enhancing the safety and reliability of offshore wind turbines. This research clarifies OWT foundation dynamics, helping researchers address challenges and optimize designs. Full article

To address the current lack of specialized equipment for offshore wind platform installation and the unresolved challenges in deploying large offshore converter stations, this paper proposes a novel T–U-shaped barge for large offshore wind structures. First, a hydrodynamic model of the T–U-shaped barge is constructed and analyzed in ANSYS-AQWA. The influence of resonance occurring in the gap at the U-shaped stern on the frequency-domain model of the T–U-shaped barge is investigated. Subsequently, two installation configurations are examined: loading at the bow and loading at the stern of the T–U-shaped barge. This study comprehensively considers key components of the float-over installation system, including leg mating units (LMUs), deck support units (DSUs), fenders, and mooring cables. The results show that, for both installation schemes, the dynamic load distribution on each LMU evolves as the load-transfer stage progresses, and the sensitivity to wave period varies across different load-transfer stages, even under the same operating condition. This study evaluates the performance of the proposed T–U-shaped barge in the float-over installation of large offshore converter stations, demonstrating that its distinctive configuration endows it with strong functionality and provides valuable references for optimizing offshore wind-structure installation methods, as well as for the design and manufacturing of installation equipment. Full article

This study presents the design and performance assessment of suction anchor foundations for an integrated offshore wind–solar–aquaculture system located in Jiangsu Sheyang, China. The project represents one of the first practical demonstrations of coupling renewable energy production with large-scale marine aquaculture on a shared floating platform. Using three-dimensional numerical simulations in FLAC3D and ABAQUS, the study evaluates the anchors’ bearing capacity, structural safety, and fatigue performance under ultimate (ULS), accidental (ALS), and fatigue (FLS) limit states. The analysis incorporates site-specific geotechnical conditions, seabed scour, and installation deviations, providing a realistic framework for foundation design in layered coastal sediments. Results confirm that the suction anchor system meets international safety requirements (DNV, CCS) and maintains robust performance throughout its service life. The findings demonstrate that scour depth and installation accuracy are critical factors governing anchor reliability and offer practical insights for updating offshore foundation design standards in future multifunctional renewable–aquaculture developments. Full article

As offshore wind power moves into deeper waters, large-scale electrical platforms are key to efficient power transmission. However, their heavy topside modules create major installation challenges. As traditional lifting methods are inadequate, the float-over method has become a viable solution for installing topside modules, but it is essential to study the structural responses to collisions during the process to ensure construction and equipment safety. This study establishes a physical model of the offshore converter station at a 1:65 scale based on the elastic force-gravity similarity principle. Assuming the barge carrying the topside module descends at a constant speed, the study investigates the dynamic response of the platform during the float-over mating process. Float-over collision tests are conducted to obtain the platform’s acceleration, strain, and displacement responses and to analyze the effects of collision speed, offset position, and Leg Mating Unit (LMU) stiffness on the dynamic structural response characteristics. The results show that as collision speed increases from 10 mm/s to 50 mm/s, the topside acceleration response increases up to 5.7 times. Beam strain remains mostly unchanged, and displacement increases first, then decreases. Under fixed descent velocity, x-offset increases jacket strain and converter valve acceleration, while y-offset raises platform acceleration and reduces valve acceleration by approximately 20 percent. At 50 mm/s, higher LMU stiffness causes the acceleration response to first drop, then rise. These findings support safe float-over installation. Full article

This study examines the landing performance of a four-legged lunar lander equipped with magnetorheological dampers when landing on discrete lunar soil. To capture the complex interaction between the lander and the soil, a coupled dynamic model is developed that integrates flexible multibody dynamics (FMBD), granular material modeling, and a semi-active fuzzy control strategy. The flexible structures of the lander are described using the floating frame of reference, while the lunar soil behavior is simulated using the discrete element method (DEM). A fuzzy controller is designed to achieve the adaptive MR damping force under varying landing conditions. The FMBD and DEM modules are coupled through a serial staggered approach to ensure stable and accurate data exchange between the two systems. The proposed model is validated through a lander impact experiment, demonstrating good agreement with experimental results. Based on the validated model, the influence of discrete lunar regolith properties on MR damping performance is analyzed. The results show that the MR-based landing leg system can effectively absorb impact energy and adapt well to the uneven, granular lunar surface. Full article