Explore the vast range of titles available.

Floating fluid-filled membrane breakwater (FFMB) is a temporary structure that can attenuate waves in the deep sea. In this paper the hydrodynamic performance of the FFMB is analysed by using the eigenfunction expansion boundary element method (EEBEM) and physical model experiments. A general motion equation is derived that considers both the dynamic tension and curvature of the membrane. Moreover, an integral expression for the dynamic tension is provided. On this basis, a linear model for solving wave–membrane interaction is established through the EEBEM. Newly designed physical experiments are performed to verify the model and elucidate the nonlinear characteristics of the FFMB. Following verification of the model, this paper investigates the effects of various structural parameters of the FFMB on the wave transmission coefficient, reflection coefficient, horizontal wave force, vertical wave force and dynamic tension. Furthermore, the interrelationship between the structural resonant response and the hydrodynamic performance is elucidated, and the optimal density and filling ratio of the FFMB for engineering applications are proposed. The results demonstrate that the numerical and experimental results are in good agreement, indicating that the model and the motion equation are both practical and highly accurate. By optimizing the structural parameters, the FFMB is capable of effectively attenuating waves within a specific frequency band, while minimizing the wave force.

The present study investigates the scattering of ocean wave and currents by an inverted T-type lightweight surface-piercing wave barrier that is situated over a uniform sea bed. To handle the boundary value problem (BVP), an iterative boundary element method (BEM) has been used. To analyze the efficacy of employing thin wave barriers, the impact of porosity, relative submergence depth and width of the barrier on the hydrodynamic properties (like wave force, reflection, dissipation, and transmission) are investigated in the presence of ocean currents. The simulated outcomes demonstrate that the Doppler Shift effect of the frequency due to the presence of ocean currents significantly influences the behaviour of the aforementioned hydrodynamic properties. Moreover, these simulated results also demonstrate that the use of lightweight wave barriers provides a better wave energy dissipation compared to the bulky submerged structures.

Phase and stoichiometry control are crucial to employ the superconducting properties of FeSe thin films, and with it the previously reported interfacial boost in superconductivity promoted by the SrTiO 3 surface. This work investigates how growth parameters influence the phase and chemical composition in FeSe layers on SrTiO 3 (001) substrates by molecular beam epitaxy. In the first part, the influence of substrate surface preparation on the stabilization of the respective FeSe phase and film morphology is evaluated by atomic force microscopy (AFM), reflection high energy-electron diffraction (RHEED), and X-ray diffraction (XRD). Continuous, phase-pure β-FeSe layers were observed on non-ideally prepared substrates only at high growth temperatures, whereas optimized surface preparation yielded similar results at much reduced temperatures. Although RHEED indicated atomically smooth film topography, AFM revealed pronounced island growth. In the second part, the stoichiometry of phase-pure β-FeSe films grown under different growth conditions is evaluated by XRD and structural calculations. Supporting transport measurements identified a narrow growth window to satisfy the stoichiometric requirement for superconducting β-FeSe thin films.

This study explores the fabrication of tannic acid-crosslinked gelatin nanofibers via electrospinning, followed by helium and nitrogen plasma treatment to enhance their biofunctionality, which was assessed using fibroblast cells. The nanofibers were characterized using scanning electron microscopy, atomic force microscopy, attenuated total reflection Fourier transform infrared spectroscopy, X-ray diffraction, and water contact angle measurements before and after treatment. Helium and nitrogen gas plasma were employed to modify the nanofiber surfaces. Results indicated that helium and nitrogen plasma treatment significantly increased the hydrophilicity and biofunctionality of the nanofibers by 5.1° ± 0.6 and 15.6° ± 2.2, respectively, making them more suitable for human skin fibroblast applications. To investigate the impact of plasma treatment on gelatin, we employed a computational model using density functional theory with the B3LYP/6-31+G(d) method. This model represented gelatin as an amino acid chain composed of glycine, hydroxyproline, and proline, interacting with plasma particles. Vibrational analysis of these systems was used to interpret the vibrational spectra of untreated and plasma-treated gelatin. To further correlate with experimental findings, molecular dynamics simulations were performed on a system of three interacting gelatin chains. These simulations explored changes in amino acid bonding. The computational results align with experimental observations. Comprehensive analyses confirmed that these treatments improved hydrophilicity and biofunctionality, supporting the use of plasma-treated gelatin nanofibers in skin tissue engineering applications. Gelatin’s natural biopolymer properties and the versatility of plasma surface modification techniques underscore its potential in regenerating cartilage, skin, circulatory tissues, and hamstrings.

The hydroelastic interaction between water waves and multiple submerged porous elastic plates of arbitrary lengths in deep water is examined using the Galerkin approximation technique. We observe the influence of flexible porous plates of arbitrary lengths by analysing the reflection coefficient, dissipated energy and wave forces acting on the plates. Results are presented for various values of angle of incidence, separation lengths of plates, porosity levels, submergence depth and flexural rigidity. The convergence and accuracy of the method are verified by comparing the results with existing literature. The significant impact of flexural rigidity in the presence of porosity on wave reflection, dissipated energy and wave forces is demonstrated. Moreover, a notable reduction in wave load is observed with an increase in the number of plates.

Moiré superlattices in van der Waals heterostructures represent a highly tunable quantum system, attracting substantial interest in both many-body physics and device applications. However, the influence of the moiré potential on light-matter interactions at room temperature has remained largely unexplored. In our study, we demonstrate that the moiré potential in MoS 2 /WSe 2 heterobilayers facilitates the localization of interlayer exciton (IX) at room temperature. By performing reflection contrast spectroscopy, we demonstrate the importance of atomic reconstruction in modifying intralayer excitons, supported by the atomic force microscopy experiment. When decreasing the twist angle, we observe that the IX lifetime becomes longer and light emission gets enhanced, indicating that non-radiative decay channels such as defects are suppressed by the moiré potential. Moreover, through the integration of moiré superlattices with silicon single-mode cavities, we find that the devices employing moiré-trapped IXs exhibit a significantly lower threshold, one order of magnitude smaller compared to the device utilizing delocalized IXs. These findings not only encourage the exploration of many-body physics in moiré superlattices at elevated temperatures but also pave the way for leveraging these artificial quantum materials in photonic and optoelectronic applications. The authors observe that the atomic reconstruction in MoS 2 /WSe 2 heterobilayers with large lattice mismatch results in the most significant periodic strain distribution, contributing to the effective localisation of excitons within moiré potential traps at room temperature.

A theoretical model of the interaction between a following current and a semi-infinite floating ice sheet under compressive stress near a vertical impermeable wall is developed, within the scope of linear water wave theory, to study the hydroelastic behavior. The conceptual framework defining the buoyant ice structure incorporates the tenets of elastic beam theory. The associated fluid dynamics are governed by strict adherence to the potential flow paradigm. To resolve the undetermined parameters appearing in the Fourier series decomposition of the potential functions, investigators systematically apply higher-order criteria detailing the coupling relationships between modes. The current results are compared with a specific case of results available in the literature, and the convergence analysis of the analytical solution is made for computational accuracy. Further, the free edge conditions are applied at the edge of the floating ice sheet, and the effects of current speed, compressive stress, the thickness of the ice sheet, flexural rigidity, water depth on the strain, displacements, reflection wave amplitude, and the horizontal force on the rigid vertical wall are analyzed in detail. It is found that the higher values of the following current heighten the strain, displacements, reflection amplitude, and force on the wall. The study’s outcomes are considered to benefit not just cold region design applications but also the engineering of resilient floating structures for oceanic and offshore environments, and to the design of marine structures.

The widespread deployment of offshore wind turbines requires the use of fast, low-cost, and reliable installation methods. While impact pile driving is predominantly used for offshore monopile foundations, vibratory pile driving provides an interesting alternative. The selection of a suitable installation technique is based on cost, marine environment, noise pollution, and soil conditions. To study installation effects, this research aims to develop 1g laboratory scale tests of both impact and vibratory pile driving in a sand filled and saturated container. Numerical models are employed to study the dynamic behavior of the 1g scale test, and are used to design (and optimize) the test setup. Particular attention is related to the reflection of waves at the boundary of the container and the frequency content of the vibratory and impact driving force, as to get the best correspondence with the full-scale pile installation in situ. The numerical model includes (1) a multi-body dynamic models to compute the impact or vibratory loads on the pile head, and (2) a finite element model of the sand box – pile system. This allows us to study the dynamic interaction between the pile and the soil, wave propagation in the sand box, and estimate the soil’s response. The comparison of both scales is then used to optimize the test setup, achieving a good correspondence to a full–scale test, both statically and dynamically.

Either difficulty of dispersion of carbon nanotubes (CNTs) in the solvent or low compatibility between polymeric chains of membrane and CNTs results in major drawbacks to using CNTs in the structure of mixed matrix membranes. CNTs’ functionalization has already gained increasing attention to overcome such problems. Herein, polyethersulfone-based mixed matrix membranes incorporated with citric acid–amylose-decorated multiwall carbon nanotubes (Am–MWCNTs–CA) were fabricated. These new synthesized nanoparticles and nanocomposite membranes were characterized by spectroscopic measurement methods such as IR spectroscopy, UV–Vis spectroscopy, 1 H NMR spectroscopy, 13 C NMR spectroscopy, water contact angle, attenuated total reflection-infrared, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The pure water flux of the modified membrane incorporated with 0.5 w/v% Am–MWCNTs–CA increased over 130% in comparison with the unmodified membrane. Flux recovery ratio results illustrated that the membrane modified with 0.5 w/v% Am–MWCNTs–CA showed superior antifouling capacity of over 95.2%. SEM and AFM images showed significant and observable changes in surface morphology along with the formation of large finger-like macrovoids in the presence of Am–MWCNTs–CA. The presence of more COOH and OH functional groups on the surface of the modified membranes enforced the Donnan exclusion theory to reject rather divalent ions due to the migration of Am–MWCNTs–CA nanocomposite to the surface of membranes. In addition, humic acid removal capability of the prepared membranes was also calculated to be as high as 97.4% for the membrane embedded with 0.5 w/v% Am–MWCNTs–CA (M 3 ).

The present work analyzes the interaction of oblique waves by a porous flexible breakwater in the presence of a step-type bottom. The physical models for both scattering and trapping cases are considered and developed within the framework of small amplitude water-wave theory. Darcy’s law is used to model the wave interaction with the porous medium. It is assumed that the varying bottom extends over a finite interval, connected by a finite length of uniform bottom near an impermeable wall, and a semi-infinite length of bottom in the open water region. The boundary value problem is solved using the eigenfunction expansion method in the uniform bottom regions, while a modified mild-slope equation (MMSE) is used for the region with the varying bottom. Additionally, a mass-conserving jump condition is employed to handle the solution at slope discontinuities in the bottom. A system of equations is derived by matching the solutions at interfaces. The reflection coefficient and force on the breakwater and impermeable wall are plotted and analyzed for various parameters, such as the length of the varying bottom, depth ratio, angle of incidence, and flexural rigidity. It is observed that moderate values of flexural rigidity and depth ratio significantly contribute to an optimum reflection coefficient and reduce the wave force on the wall and breakwater. Remarkably, the outcomes of this study are assumed to be applicable in the construction of this type of breakwater in coastal regions.