Search Results (145)

Floods are among the most frequent and destructive natural hazards, causing significant socio-economic losses worldwide. This paper presents a comprehensive review of floodwall technologies, focusing on the integration of ultra-high-performance fibre-reinforced concrete (UHPFRC) to enhance structural and hydraulic performance. Flood protection systems are categorized into permanent, demountable, and temporary, and are evaluated based on parameters such as activation time, seepage resistance, and lifecycle cost. This review examines key structural applications, including floodwall barriers, wave-energy floaters, and retaining walls, in which UHPFRC provides significant advantages such as reduced material consumption, improved impact resistance, and increased durability in harsh environmental conditions. Additionally, recent advancements in floodwall systems are critically assessed through experimental investigations, numerical modelling, and hydraulic performance under varied loading and flow conditions. The analysis reveals that while UHPFRC systems can reduce material volumes by up to 73% and carbon emissions by 49% compared to conventional reinforced concrete, their adoption is currently limited by a lack of dedicated design standards. Based on a synthesis of peer-reviewed studies (2010–2026), findings indicate that autonomous, buoyancy-driven UHPFRC barriers offer the highest reliability in high-risk zones, whereas manual modular systems remain limited by human-factor vulnerabilities during rapid deployment. Critical research gaps are identified—specifically the need for standardized constitutive models for UHPFRC in hydrostatic environments and extensive long-term field validation—to support the transition toward resilient, smart urban flood defence infrastructure. Full article

This paper deals with a time-domain methodology for nominal stress-based, screening-level fatigue assessment of semi-submersible FWT hulls, using a 10-MW semi-submersible FWT as a case study. A comprehensive procedure is outlined for both short- and long-term fatigue analysis, emphasizing the influence of wind and wave loads, as well as the probability distributions of environmental conditions. A fully coupled dynamic analysis of the FWT, employing a multibody floater, is conducted to compute internal global loads and time-domain nominal stresses on the hull structure. Short-term fatigue damage is evaluated across various wind-wave directions, environmental conditions, and random wind and wave samples, identifying critical loading scenarios. For long-term assessment, 10,182 one-hour time-domain simulations are conducted across three wind-wave directions for five offshore sites in the North Sea and one site in the China Sea. Fatigue damage at different locations of the hull structure is estimated for each offshore site, with results discussed in the context of screening-level nominal fatigue assessment and identification of fatigue-critical regions. The insights gained from this study form a basis for validating simplified and computationally efficient fatigue analysis procedures in an accompanying paper. Additionally, the findings support the design optimization of hull structures. Limitations of the present study are identified, pointing to future research directions aimed at mitigating fatigue risks. Full article

This study presents a hydrodynamic assessment of a toroidal wave energy converter (WEC) operating under low-energy conditions of the west coast of Mexico. Performance analysis incorporates the coupling surge, heave, and pitch motions. To investigate mooring–device interaction, two mooring configurations were examined: (A) a single catenary system and (B) a catenary system with a surface-floating buoy. The WEC was evaluated under operational conditions, operational conditions with a constant surface current, and extreme seas. The results show that under operational conditions, the WEC-mooring B configuration achieves higher energy capture than the WEC-mooring A configuration, with performance peaks at 13 s and 11 s, respectively. The presence of a surface current does not significantly influence absorbed power. Under extreme conditions, mooring B reduces mooring-line stresses but causes greater horizontal foundation forces and increased floater drift compared to mooring A. When mooring effects are included, mooring A’s performance is advantageous because it shifts peak energy capture toward the dominant sea states at the study site. This maintains better station-keeping capability and achieves a maximum capture width ratio (CWR) of approximately 0.5. Full article

With the rapidly growing global demand for clean energy, offshore wind power has become an important renewable energy source. To clarify how the principal dimensions affect the performance of a 15 MW-class floating wind turbine platform in 100 m water depth, this paper proposes a steel-concrete hybrid semi-submersible platform and systematically performs a parametric sensitivity analysis. The platform adopts a three-column configuration with heave tanks. The upper columns and cross braces are made of steel, while the lower hexagonal columns, pontoons, and heave tanks are constructed from concrete, significantly reducing steel consumption while satisfying structural and stability requirements. Focusing on three key design variables—draft, column spacing, and column diameter—this study establishes a unified normalized sensitivity analysis framework. It quantitatively evaluates their influence on platform mass, intact stability, natural periods, and fully coupled dynamic responses (including surge, heave, pitch motions, and mooring line tensions) under both operational and extreme conditions. The results reveal distinct roles of the principal dimensions in governing the platform dynamics: column spacing is the most sensitive parameter for tuning pitch response, restoring stiffness, and stability; increasing draft effectively suppresses heave and pitch responses but has only a limited effect on low-frequency surge motions; and column diameter strongly affects the natural periods of heave and pitch. Notably, dynamic responses exhibit significant nonlinear characteristics with variations in column diameter. When the diameter exceeds 110–120% of the baseline value, the peak pitch response under extreme sea states shows a deteriorating inflection point, accompanied by an accelerated surge in peak mooring loads. This indicates that excessive increases in column diameter may cause wave excitation forces to become dominant, thereby compromising the overall dynamic safety of the system. This paper identifies the governing geometric parameters for different motion modes and their control boundaries, providing a quantifiable and generalizable basis for the multi-objective collaborative design and cost reduction optimization of 15 MW steel-concrete hybrid semi-submersible floating wind turbine platforms. Full article

During the transportation and storage of liquefied natural gas (LNG), sloshing in partially filled cargo tanks poses significant risks to structural integrity and operational safety. Conventional anti-sloshing devices, such as internal baffles, are incompatible with membrane-type tanks due to strict requirements on internal geometry and material integrity. To address this challenge, this study proposes an eccentric foam floater (EFF), which enhances energy dissipation through controlled mass asymmetry without modifying the tank’s internal configuration. Building upon the buoyant-ball concept, the EFF introduces an offset between geometric center and center of mass, thereby promoting additional rotational motion, inter-floater and floater–wall friction, and fluid–structure interaction effects. Model experimental investigations using a six-degree-of-freedom motion platform, combined with discrete element method (DEM) simulations, demonstrate that the EFF consistently outperforms its homogeneous counterpart in suppressing sloshing-induced pressure fluctuations across a broad range of excitation conditions. The results highlight the potential of mass eccentricity as a design principle for passive, structure-preserving sloshing mitigation in membrane LNG tanks. Full article

Floating wind turbines are becoming increasingly mainstream. Floating wind turbines have strengths in terms of cost-efficiency compared to conventional wind turbines. Comparisons between floating and conventional wind turbines can be easily conducted through simulations. In this paper, we estimate the CAPEX and LCOE of fixed and floating offshore wind farms following the INNU cost model with LIR rotor technology and hybrid floater technology. Full article

Background: Senior–Loken syndrome (SLS) is a rare autosomal recessive ciliopathy classically defined by the concurrence of nephronophthisis, frequently progressing to end-stage renal disease (ESRD), and retinal dystrophy, most commonly presenting as retinitis pigmentosa (RP). Given its phenotypic overlap with other renal–retinal syndromes, establishing a definitive diagnosis necessitates integrated clinical evaluation and molecular confirmation. Case Presentation: A 28-year-old Chinese female presented with a two-month history of binocular floaters. Her medical history was significant for ESRD of five years’ duration, managed with maintenance hemodialysis. Ophthalmic assessment revealed retinal pigment mottling along the inferior temporal arcades and generalized arterial attenuation. Spectral-domain optical coherence tomography demonstrated outer retinal thinning with loss of the ellipsoid zone at corresponding locations. Perimetry confirmed visual field constriction, and full-field electroretinography showed severely reduced rod- and cone-mediated responses. Genetic testing was performed and a pathogenic variant in the NPHP1 gene was identified. Segregation studies confirmed both parents as heterozygous carriers, consistent with autosomal recessive inheritance. Collectively, these findings established a diagnosis of SLS. Conclusions: This case reinforces that SLS should be considered in the differential diagnosis of any young patient exhibiting RP alongside chronic kidney disease, particularly in the setting of early-onset ESRD. It also illustrates the essential role of a coordinated, multidisciplinary approach—encompassing nephrology, ophthalmology, and genetics—in diagnosing complex ciliopathies. Genetic confirmation not only validates the clinical diagnosis but also provides a foundation for family counseling, prognostic stratification, and future eligibility for gene-specific therapeutic trials. Full article

Blade pitch control is one of the most important control systems for a wind turbine: blade pitch controller malfunction can lead to increased vertical bending moment at the tower base, which may result in structural failure. This study investigated the collapse behavior mechanism at the tower root due to an extreme event of blade pitch malfunction for onshore and spar-floating wind turbines. An aero-hydro-elastoplastic coupled analysis tool previously developed and validated by one of the authors was utilized to capture the structural response at the tower root in elastic and plastic regions. Three strength models—(i) SM-01, (ii) SM-02, and (iii) SM-03—were selected to demonstrate the collapse behavior mechanism of onshore and spar-floating 5 MW wind turbines in a time-series simulation. The damage in the plastic region, termed the collapse extent, was evaluated at the collapsing section. Moment–rotational angle relationships are discussed under the same wind conditions. The tower vibrations were found to dominate the structural response of the onshore wind turbine, whereas the tower vibrations and floater response dominate the spar-floating wind turbine response during the failure event. The collapse extent of the spar-floating wind turbine was found to be 8 times larger than the onshore wind turbine under the same wind conditions. Furthermore, simulations were carried out for the spar-floating wind turbine to understand the effect of incoming waves on the collapse behavior: the collapse extent increases as the wave amplitude and period increase under the same wind conditions. Full article

This study presents a series of hydrodynamic experiments on a novel pontoon-type offshore floating photovoltaic (OFPV) structure, designed to improve wave attenuation performance and platform stability in marine environments. Using a 1:14 Froude-scaled physical model capable of representing different connector stiffness levels, nine structural configurations were tested, covering four array scales, three stiffness levels, and two floater sizes. Experiments were conducted under regular wave conditions, with structural responses measured at three representative positions: wave-facing front (T1), mid-array (T2), and leeward side (T3). Recorded parameters included surge acceleration, heave acceleration, pitch angle, and heave displacement. Results show that increasing array scale consistently reduced motion amplitudes at all positions, with heave acceleration at T3 substantially decreased compared with the smallest array. Enhancing connector stiffness significantly suppressed dynamic motions, particularly downstream, while larger floaters notably reduced heave responses under short-period waves. Despite variations in magnitude, response trends with respect to wave period remained broadly consistent across configurations. These findings provide quantitative evidence and engineering guidance for optimizing array configuration, connector stiffness, and floater dimensions to enhance the hydrodynamic performance and operational reliability of large-scale offshore FPV platforms. Full article

Cavity limitations and interspecific competition render large macaws valuable models for elucidating the integration of parental care, pair-bond maintenance, and nest defense across reproductive stages. Through continuous video monitoring of a single artificial polyvinyl chloride nest box in the Tambopata National Reserve, Peru, we quantified the complete breeding cycle of a resident green-winged macaw (Ara chloropterus) pair and the visitation behavior of a sympatric scarlet macaw (Ara macao) pair within the same cavity. We constructed daily time budgets for 17 behaviors, categorized into seven functional groups, from motion-triggered video clips; employed multivariate tests; and generalized additive models with beta error distribution to describe the temporal changes across the five reproductive stages. The resident A. chloropterus exhibited a significant reorganization of parental investment, with early courtship behaviors transitioning to peak nest attendance and sentinel vigilance during incubation and early brooding. In later stages, locomotion increased significantly, associated with chick provisioning, whereas the frequency of allopreening remained relatively constant throughout the cycle. The visiting A. macao displayed a brief, behaviorally rich prospecting phase, characterized by nest inspection and locomotion, followed by a sharp decline in minimal activity. These divergent strategies align with owner–intruder asymmetries and floater dynamics, indicating that artificial cavities can support A. chloropterus breeding, while suggesting that additional cavities may redistribute breeding opportunities among competing macaws, a hypothesis necessitating multi-nest and multi-year evaluation. Full article

To address the issues of insulation layer damage and conductor exposure in offshore floating photovoltaic systems occurring in shallow marine regions characterized by significant tidal ranges under multi-field coupling effects, an overhead cable laying scheme based on the hybrid pile–floater structure is proposed, while its mechanical response is investigated in this paper. The motion response model of the floating platform, considering wind load, wave load, current load, and mooring load, as well as the equivalent density and mathematical model of the overhead cable are established. The mechanical response characteristics of the overhead cable are analyzed through finite element analysis software. The results indicate that the overhead cable’s mechanical response is influenced by the span length and coupled wind–ice loads. Specifically, the tension exhibits a nonlinear increasing trend, while the deflection shows differential variations driven by the antagonistic interaction between wind and ice loads. The influence of ice loads on the configuration of overhead cables is significantly weaker than that of wind loads. This study provides crucial theoretical support for enhancing the lifespan of the overhead cable. Full article

This study re-examines generational differences in media literacy and news consumption within the evolving digital landscape. It expands on the well-known dichotomy of Digital Natives and Digital Immigrants by proposing a new conceptual framework that introduces the terms Analog Anchors and Digital Floaters. These terms aim to reflect the heterogeneity and fluidity more accurately, the adaptive nature of users’ engagement with digital media. A quantitative survey was conducted using an online questionnaire distributed to Greek participants (N = 1020) through a non-probability convenience sampling method. The analysis revealed significant variations in digital literacy, news consumption habits, and skepticism toward the media across generations. Findings indicate that the relationships with technology and information are not linear or age-bound but are shaped by cultural, cognitive, and social parameters. High levels of media skepticism observed across all age groups further challenge traditional divides. As a result, this study argues for a paradigm shift that captures the complexity of media literacy in the platform era, moving from static generational labels towards a more dynamic understanding of users as Analog Anchors and Digital Floaters. Full article

Background: To evaluate the short-term effects of a dietary supplement containing curcumin, bromelain, glucosamine, chondroitin sulphate, sodium hyaluronate, type II collagen, and vitamin C on symptomatic vitreous floaters (SVFs) following Nd:YAG laser capsulotomy. Methods: Forty eyes with SVFs on the first postoperative day were randomized into a control group (standard topical therapy, n = 20) and a treatment group (oral supplement plus standard therapy, n = 20). Outcomes included best-corrected visual acuity (BCVA), contrast sensitivity (CS), and subjective scores from a non-standardized questionnaire on floater perception (QS1), interference with daily activities (QS2), and foreign body sensation (QS3). Objective evaluation was performed using two novel ultrasound-based methods: mean number of vitreous peaks (MVP) from A-scans and mean grey intensity (MGI) from B-scan images processed with ImageJ. Results: At 2 months, the treatment group showed greater improvement in CS (Δ = 0.26 LogCS, CI, 0.14–0.38; p < 0.01), QS1 (Δ = 1.10; 95% CI, 0.60–1.60; p < 0.01), QS2 (Δ = 0.90; 95% CI, 0.40–1.40; p < 0.01), QS3 (Δ = 0.90; 95% CI, 0.44–1.36; p < 0.01), MVP (Δ = 1.10; 95% CI, 0.60–1.60; p < 0.01), and MGI (Δ = 12.89 units; 95% CI, 7.84–17.93; p < 0.01). BCVA was comparable between groups (p = 0.478). Conclusions: Short-term dietary supplementation with vitreous-specific nutrients is well tolerated and associated with improvements in reducing SVFs and foreign body sensations after Nd:YAG capsulotomy and may represent a promising non-invasive therapeutic option. Full article

Mathematical modeling competency is essential for engineering students, yet significant cognitive obstacles impede their ability to apply theoretical concepts like derivatives to real-world optimization problems. This study investigates the cognitive processes and obstacles encountered by Industrial Engineering and Management students when solving applied derivative problems, utilizing the Mathematical Modeling Cycle (MMC) and Duval’s theory of semiotic registers as analytical frameworks. A qualitative case study design was employed, analyzing students’ written exam responses to an applied optimization task involving tour organization with variable pricing structures. Three representative cases were examined in detail, revealing distinct patterns of cognitive engagement. Results identified specific cognitive obstacles including misunderstanding of variables and domains, weak connections between mathematical and economic contexts, difficulties in graphical representation of constraints, and deficits in validation and critical thinking. While students demonstrated procedural fluency in symbolic manipulation and mathematical work, they struggled to coordinate between different semiotic registers (verbal, algebraic, graphical, and contextual) and failed to complete the full modeling cycle, particularly in the crucial validation stages. These findings suggest that cognitive obstacles stem from representational gaps rather than general learning difficulties, indicating the need for targeted pedagogical interventions that explicitly address transitions between semiotic registers and emphasize the iterative nature of mathematical modeling in engineering contexts. Full article

Background and clinical significance: Tranexamic acid (TXA) is commonly used for menorrhagia. Common side effects include diarrhoea, nausea, and vomiting. However, more serious and rare side effects, including embolism, thrombosis, and seizures, are less commonly considered. Case presentation: We report the case of a 39-year-old woman of Asian origin who presented after a first-time seizure while driving, following starting tranexamic acid for menorrhagia seven days prior. She complained of a headache, nausea, neck stiffness, floaters, and blurred vision. Her lactate was elevated on presentation. On examination there were no neurologic abnormalities. A computed tomography (CT) head scan showed acute haemorrhagic foci along the left temporal lobe. This prompted a CT venography, which showed filling defects in the left transverse and sigmoid sinuses, in keeping with cerebral venous sinus thrombosis. MRI of the head further showed a blooming artefact, indicating secondary thrombosis of the lateral tentorial sinus on the left side extending into the vein of Labbe. Following the diagnosis of cerebral venous sinus thrombosis, the patient was started on regular levetiracetam as well as a therapeutic dose of low molecular weight heparin. Since the initial episode, she has been seizure-free for over three months now. Conclusions: This case highlights the importance of considering less common side effects of tranexamic acid in patients who are taking TXA and are presenting with first-time seizures and headaches. These patients should be monitored for embolic-related intracranial events. A careful diagnostic approach, including cerebrovascular imaging, is essential for an accurate diagnosis and effective treatment. Full article