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A novel polarization beam splitter (PBS) based on dual-core photonic crystal fiber (DC-PCF) is proposed in this work. The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetrical elliptic dual-core structure. By using the full-vector finite element method, the propagation characteristics of the proposed DC-PCF PBS are investigated. The simulation results show that the bandwidth of the proposed DC-PCF PBS can reach to 340 nm, which covers the S + C + L + U communication bands, the shortest splitting length is 1.97 mm, and the maximum extinction ratio appears near wavelength 1550 nm. Moreover, the insertion loss of the proposed DC-PCF PBS is very low. It is believed that the proposed DC-PCF PBS has important applications in the field of all-optical communication and network. [ABSTRACT FROM AUTHOR]

The rapid development of the marine industry offers more opportunities to combine aquaculture with other marine uses. This study reports a trestle-netting enclosure aquaculture facility that combines an offshore steel trestle with a marine aquaculture facility in which the trestle acts as a supporting substructure. In this study, the numerical models include one configuration without netting and three configurations with netting in different regular waves, which are generated based on stream function theory owing to nonlinear wave problems. The time series of the horizontal wave forces were obtained and analyzed in the four models. Numerical results showed that netting can significantly increase the positive amplitudes of horizontal wave forces, and the wave forces of trestle with the lee-side netting were almost smaller than those of the wave-side netting. Moreover, we investigated the nonlinear features of the wave forces and profiles. The horizontal asymmetry factors of the wave forces are affected by those of the wave profiles, while the vertical asymmetry factors of the wave forces are affected by those of the wave slope profiles. The effects of the netting on the force-positive amplitudes agree with the horizontal asymmetry factors of the wave forces but not with the vertical asymmetry factors. • Finite element models of trestle-netting enclosure aquaculture facility are established. • Hydrodynamic analysis of the complex models is conducted under nonlinear waves. • Effects of netting on wave loads and the nonlinear features of wave loads is discussed. [ABSTRACT FROM AUTHOR]

With the growth of global population, the demand for seafood has been increasing. Aquaculture as a sustainable industry provides a new direction to satisfy the rising demand for seafood. However, typhoons, a common disaster in coastal areas, can cause massive waves that can threaten the safety of aquaculture facilities. Therefore, studying the facilities' failure probability under typhoon waves with different return periods is crucial. The example of offshore high-density polyethylene net cages in the seas near Guishan Island, Zhuhai, China, was examined in this study. The wave conditions for different return periods for these seas were predicted using the SWAN+ADCIRC model and the local wave statistics for the last 30 years. Based on the prediction results, the hydrodynamic loads and stresses of the primary cage structure (floating collar, nets, and mooring lines) in typhoon waves at different return periods were calculated using the lumped-mass and finite element methods. Meanwhile, the failure probability of the cage components was analyzed based on the Monte Carlo method. According to the failure probability and cost of different components, the suitable size of the each of the cage components in the representative seas was studied. This study affords a reference for the design of the cage and improve the aquaculture insurance. • Relation between typhoon waves and failure probability of HDPE net cage components. • SWAN+ADICRC model combined with local hydrographic data to predict typhoon waves. • Lumped-mass and finite element methods for hydrodynamic loads on components. • Quantitative response relationship established using Monte Carlo method. [ABSTRACT FROM AUTHOR]

The mechanical properties of three‐dimensional (3D) braided composites are related to damage evolution. However, the multi‐scale damage mechanism of 3D braided composite shafts remains unclear. The main purpose of this article is to propose a shell‐based multiscale finite element model for effectively predicting the compressive and torsional properties of 3D four‐directional (3D4d) braided composite shafts. Considering the relation between equivalent ply angles and yarn structures, the multiscale model was developed based on a universal tubular unit cell. The equivalent ply angle was derived through the yarns' local braiding and horizontal orientation angles, and the elastic properties of each equivalent ply were derived through the stiffness averaging method. Both derivations were achieved by creatively utilizing deformation gradient theory and Nanson's formula from continuum mechanics. LaRC04 failure criteria and energy‐based damage evolution law were implemented to characterize the equivalent UD‐ply's damage behaviors. The proposed model was validated experimentally, and good agreements were observed between the failure morphologies and load–displacement curves of FEA and experimental results. The results show that the fiber tension and compression damages are the major failure modes of 3D4d braided composite shafts under compressive and torque loads, respectively. Finally, a parametric study was carried out and compared with that from other literature to clarify the meaning of this article in relevant studies. It provides an efficient and useful tool for the design and manufacturing of 3D4d braided composite shafts with desirable mechanical properties. Highlights: A shell‐based hierarchical multiscale model is developed for 3D braided composite shafts.An analyzing method is developed to investigate the tubular yarn structures.A large‐scale torsional experimental scheme is developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A process-structure-performance modeling framework of 3D rotary braided composites is established. • An algorithm of characterizing the carrier paths in the continuous rotary braiding process is developed. • Tensile mechanical properties and failure mechanism of 3D rotary-four-directional braided composites are predicted. The mechanical properties of braided composites are sensitive to the braiding process. However, the relations between process parameters, yarn structures and mechanical properties of three-dimensional (3D) rotary braided composites have not been investigated. In this study, we aim to establish a model capable of characterizing the yarn structures and mechanical properties of 3D rotary braided composites by treating braiding angles as primary variables. Carrier motions on the bedplate were traced by mathematical functions, where corresponding yarn spatial paths within a representative volume element (RVE) were explored. A parametric finite element model (FEM) of 3D rotary-four-directional (3DR4d) braided composites was established considering realistic yarn cross-sections. A progressive damage model was used to predict the mechanical performance of the composites. Experiments were conducted to verify the proposed model. The results show that the ideal yarn topology of the rotary braided composites is similar to the lattice structure. In addition, the longitudinal tensile modulus and strength of 3DR4d braided composites increase with the decreased braiding angles, while increasing with the increased fiber volume fractions. According to damage analysis, longitudinal tension and transverse shear are the dominant failure modes of 3DR4d composites with small and large braiding angles, respectively. [ABSTRACT FROM AUTHOR]

A novel sheet-pile groin structure consisting of row piles and a tied sheet has been introduced to resist the impact of tidal bores in recent years. However, the dynamic responses of the structure under tidal bore loads have not been carefully studied before. This paper proposed an analytical solution for the dynamic responses of a sheet-pile groin subjected to transient lateral excitation. To take the flexural and longitudinal vibrations into consideration, the piles and the sheet are modeled by Timoshenko beam (TB) theory and a one-dimensional rod, respectively. The soil around the piles is simulated by the dynamic Winkler foundation model. The excitation is considered by a lateral concentrated point load acting on the front pile. On this basis, the governing equations are constructed in the time domain and solved in the frequency domain, while the time-domain responses are obtained using the inverse Fourier transform. The accuracy of the presented analytical solution is validated by comparison with the results obtained from finite element method (FEM) simulation. The effects of the properties of the sheet, piles and soil on the dynamic responses are investigated through a comprehensive parametric study. • Dynamic responses of the sheet-pile groin subjected to a transient lateral excitation are developed. • The mathematical model takes the flexural and longitudinal vibrations into consideration to simulate the sheet-pile groin. • Velocity responses of the sheet-pile groin in time and frequency domain depend on the stiffness of the sheet-pile. • The higher shear wave velocity of the soil corresponds to a greater resonance frequency. [ABSTRACT FROM AUTHOR]